Capacitor

ABSTRACT

A capacitor is provided, which allows a user to readily change or adjust its capacitance value. The capacitor includes a dielectric film, which includes first and second conductor layers disposed on opposite surfaces thereof, and which is wound into a rod shape. First and second electrodes are led out from the first and second conductor layers, respectively. At least one of the first and second conductor layers includes an area-changeable conductor pattern, which is disposed (e.g., exposed) on an outer circumference side of the capacitor wound into the rod shape to receive physical treatment (e.g., cutting, connecting) from outside to thereby change the size of a conductor area of the at least one of the first and second conductor layers. Thus, the physical treatment changes the conductor area of the conductor layers, to thereby selectively set or adjust the capacitance value of the capacitor.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority under 35 U.S.C. 119(a) ofJapanese Application No. 2012-128834, filed Jun. 6, 2012, the entirecontent of which is incorporated herein by reference.

BACKGROUND

1. Technical Field

This invention relates to a capacitor, particularly to a film capacitorthat is suitable to be used as, e.g., a capacitor for setting theresonant frequency of a resonant circuit or a capacitor for setting thetuning frequency of a tuned circuit, and allows change or adjustment ofthe capacitance value.

2. Description of the Related Art

A coordinate input device of an electromagnetic induction system isconfigured with a position detecting device, which includes a sensor inwhich a large number of loop coils are disposed along the X-axisdirection and the Y-axis direction of coordinate axes, and a pen-shapedposition indicator, which has a resonant circuit composed of a coilwound around a magnetic core and a capacitor, as disclosed in patentdocument 1 (Japanese Patent Laid-open No. 2002-244806), for example.

The position detecting device supplies a transmission signal with apredetermined frequency to the loop coil of the sensor, to betransmitted to the position indicator as electromagnetic energy. Theresonant circuit of the position indicator is so configured as to have aresonant frequency according to the frequency of the transmission signaland stores the electromagnetic energy based on electromagnetic inductionbetween the resonant circuit and the loop coil of the sensor. Then, theposition indicator returns the electromagnetic energy stored in theresonant circuit to the loop coil of the sensor of the positiondetecting device.

The loop coil of the sensor detects this electromagnetic energy from theposition indicator. The position detecting device detects the coordinatevalues in the X-axis direction and the Y-axis direction on the sensor,indicated by the position indicator, based on the position of the loopcoil that has supplied the transmission signal and the position of theloop coil that has detected the electromagnetic energy from the resonantcircuit of the position indicator.

This kind of position indicator has such a configuration that a forceapplied to the core body of the pen-shaped position indicator, i.e., awriting pressure, is transmitted to the position detecting device as achange in the resonant frequency (or the phase) of the resonant circuit,such that the position detecting device can detect the writing pressure.As the configuration to change the resonant frequency of the resonantcircuit in association with this writing pressure, there are two types:a type of changing the inductance value of the resonant circuit inassociation with the writing pressure, and a type of changing thecapacitance of the capacitor of the resonant circuit in association withthe writing pressure.

The position indicator described in the above-described patent document1 is one example of the type of changing the inductance value of theresonant circuit. FIG. 24 shows the schematic configuration of oneexample of a related-art pen-shaped position indicator 100 of this type.The position indicator 100 of this example of FIG. 24 has, in a hollowcylindrical chassis (case) 111, a ferrite core 104 as a magnetic core,around which a coil 105 forming a resonant circuit is wound, and aferrite chip 102 as an example of a magnetic body used for changing theinductance value. In addition, the position indicator 100 includesplural capacitors 115 a to 115 h for resonance, which are connected inparallel with respect to the coil 105.

FIG. 24, which is a sectional view of the position indicator 100, showsthe state in which the coil 105 is wound around the ferrite core 104 forexplanation. As shown in FIG. 24, the position indicator 100 has aconfiguration in which the ferrite core 104, around which the coil 105is wound, and the ferrite chip 102 are opposed to each other with theintermediary of an O-ring 103, and the ferrite chip 102 gets closer tothe ferrite core 104 due to application of pressing force (writingpressure) to a core body 101. The O-ring 103 used here is a ring-shapedelastic member obtained by forming an elastic material such as syntheticresin or synthetic rubber into the shape of an alphabetical character“O.”

Furthermore, in the case 111 of the position indicator 100, thefollowing parts are housed besides the above-described parts: a printedboard 114 on which the above-described plural capacitors 115 a to 115 hfor resonance are disposed; a board holder 113 to hold this printedboard; a connecting line 116 for connecting the coil 105 to thecapacitors 115 a to 115 h for resonance on the printed board 114 to forma resonant circuit; and a buffering member 117. The positions of themare fixed by a cap 112.

When the ferrite chip 102, against which the core body 101 serving asthe pen tip abuts, is brought closer to the ferrite core 104 accordingto pressing force applied to the core body 101, the inductance of thecoil 105 wound around the ferrite core 104 changes in association withthis, so that the phase (resonant frequency) of electromagnetic wavestransmitted from the coil 105 of the resonant circuit changes. Theposition detecting device detects the change in the phase (resonantfrequency) of the electromagnetic waves received from the positionindicator by the loop coil to thereby detect the writing pressureapplied to the core body of the position indicator.

Furthermore, in the example of FIG. 24, a push switch 118 as a switchcircuit is provided on the printed board 114. A pressing part exposed tothe outside of the case 111 through a penetrating hole (not shown) madein the side surface of the case 111 is pressed by the user. Thereby,this push switch 118 is turned on/off. This push switch 118 controlsconnection/disconnection of the capacitors 115 e to 115 h among theplural capacitors 115 a to 115 h for resonance to/from the resonantcircuit as described later. Therefore, the capacitance value of thecapacitor connected in parallel in the resonant circuit is changed byturning on/off the push switch 118. Thus, the phase (resonant frequency)of the electromagnetic waves transmitted from the coil of the resonantcircuit to the position detecting device changes.

The position detecting device can detect the operation of the pushswitch 118 of the position indicator 100 by detecting the change in thephase (frequency) of the electromagnetic waves received from theposition indicator 100 by the loop coil. The on/off-operation of thepush switch 118 detected by the position detecting device is assignedvarious functions, such as a decision (confirmation) operation input,for an electronic apparatus such as a personal computer thatincorporates or is externally connected to the position detectingdevice.

A circuit configuration example of the position detecting device thatdetects the indicated position and the writing pressure by using theabove-described position indicator 100 will be described with referenceto FIG. 25. FIG. 25 is a block diagram showing a circuit configurationexample of the position indicator 100 and a position detecting device202 included in a portable apparatus such as a smartphone.

The position indicator 100 includes a resonant circuit composed of thecoil 105 and the capacitors 115 a to 115 h. As described above, the coil105 is wound around the ferrite core 104 and its inductance valuechanges depending on the distance from the ferrite chip 102.

In the position indicator 100, the capacitance value of the capacitorconnected in parallel to the coil 105 changes in association withturning-on/off of the push switch 118 and thus the resonant frequency ofthe resonant circuit changes as described above. The position detectingdevice 202 detects the shift of the resonant frequency (phase) of theresonant circuit of the position indicator 100 to thereby performdetection of writing pressure to be described later and detection ofoperation of the push switch 118.

The inductance value of the coil 105 wound around the ferrite core 104varies amongst different units. Therefore, the resonant circuit of theposition indicator 100 is so configured that the accurate resonantfrequency is obtained through adjustment of the capacitance of thecapacitor connected in parallel to the coil 105. Furthermore, in thecase of the position indicator including the above-described push switch118, the resonant frequency when the push switch 118 is in the off-stateand the resonant frequency when it is in the on-state also need to beeach adjusted.

As shown in FIG. 25, in the resonant circuit of the position indicator100, the capacitors 115 a to 115 d among the capacitors 115 a to 115 hare capacitors for being connected in parallel to the coil 105 toconfigure the resonant circuit when the push switch 118 is in theoff-state. The capacitor 115 a has comparatively high capacitance,specifically, for example, 3000 pF, and is always connected in parallelto the coil 105 to define the rough resonant frequency of the resonantcircuit when the push switch 118 is in the off-state.

The capacitors 115 b and 115 c have capacitance equal to or lower than1/10 of the capacitance of the capacitor 115 a for example, and havesuch a configuration that whether to connect them in parallel to thecoil 105 and the capacitor 115 a can be controlled by selectivelyconnecting them by a jumper line. Based on whether or not to connectthese capacitors 115 b and 115 c in parallel to the capacitor 115 a,variation in the inductance value of the coil 105 is corrected also inconsideration of variation in the capacitance value of the respectivecapacitors (115 a, 115 b, 115 c). Thereby, the resonant frequency of theresonant circuit when the push switch 118 is in the off-state isadjusted.

Moreover, the capacitor 115 d is a trimmer capacitor whose capacitancecan be changed by operating a capacitance adjustment knob and isconnected in parallel to the coil 105 and the capacitor 115 a. Fineadjustment of the capacitance is performed in a range of, for example,about 5 to 45 pF by operating the capacitance adjustment knob of thistrimmer capacitor 115 d. This allows fine adjustment of the resonantfrequency of the resonant circuit when the push switch 118 is in theoff-state.

When the push switch 118 is turned on, in addition to the capacitors 115a to 115 d, the capacitors 115 e to 115 h are further connected inparallel to configure the resonant circuit with the coil 105.

In this case, the capacitor 115 e has capacitance of, for example, 330pF and is to define the rough resonant frequency of the resonant circuitwhen the push switch 118 is in the on-state.

The capacitors 115 f and 115 g have such a configuration that whether toconnect them in parallel to the coil 105 and the capacitor 115 atogether with the capacitor 115 e when the push switch 118 is in theon-state can be controlled by selectively connecting them by a jumperline. Based on whether or not to connect these capacitors 115 f and 115g in parallel to the capacitor 115 e, variation in the inductance valueof the coil 105 is corrected also in consideration of variation in thecapacitance value of the respective capacitors (115 e, 115 f, 115 g).Thereby, the resonant frequency of the resonant circuit when the pushswitch 118 is in the on-state is adjusted.

Moreover, the capacitor 115 h is a trimmer capacitor whose capacitancecan be changed by operating a capacitance adjustment knob. Fineadjustment of the capacitance is performed in a range of, for example,about 5 to 45 pF by operating the capacitance adjustment knob of thistrimmer capacitor 115 h. This allows fine adjustment of the resonantfrequency of the resonant circuit when the push switch 118 is in theon-state.

The position detecting device 202 performs signal exchange byelectromagnetic induction with the resonant circuit of the positionindicator 100, for which the resonant frequency is adjusted in theabove-described manner, to thereby detect writing pressure andturning-on/off of the push switch in the following manner.

In the position detecting device 202, a position detection coil 210 isformed by stacking plural, specifically n in this example,X-axis-direction loop coils 211 and plural, specifically m in thisexample, Y-axis-direction loop coils 212 on each other. The respectiveloop coils configuring the plural X-axis-direction loop coils 211 andthe plural Y-axis-direction loop coils 212 are so disposed as to bearranged at equal intervals from each other and to sequentially overlapwith each other.

Furthermore, in the position detecting device 202, a selection circuit213 is provided, to which the respective X-axis-direction loop coils 211and the respective Y-axis-direction loop coils 212 are connected.

Moreover, the following units are provided in the position detectingdevice 202: an oscillator 221, a current driver 222, a switch connectioncircuit 223, a receiving amplifier 224, a detector 225, a low-passfilter 226, a sample/hold circuit 227, an A/D conversion circuit 228, acoherent detector 229, a low-pass filter 230, a sample/hold circuit 231,an A/D conversion circuit 232, and a processing controller 233. Theprocessing controller 233 is configured by a microcomputer.

The oscillator 221 generates an alternating current (AC) signal with afrequency f0. The oscillator 221 supplies the generated AC signal to thecurrent driver 222 and the coherent detector 229. The current driver 222converts the AC signal supplied from the oscillator 221 to a current andsends it out to the switch connection circuit 223. The switch connectioncircuit 223 switches the connection target (transmission-side terminalT, reception-side terminal R), to which the loop coil selected by theselection circuit 213 is connected, under control from the processingcontroller 233. Of these connection targets, the transmission-sideterminal T is connected to the current driver 222 and the reception-sideterminal R is connected to the receiving amplifier 224.

An induced voltage generated in the loop coil selected by the selectioncircuit 213 is sent to the receiving amplifier 224 via the selectioncircuit 213 and the switch connection circuit 223. The receivingamplifier 224 amplifies the induced voltage supplied from the loop coiland sends out the amplified voltage to the detector 225 and the coherentdetector 229. The detector 225 detects the induced voltage generated inthe loop coil, i.e., a reception signal, and sends it out to thelow-pass filter 226. The low-pass filter 226 has a cutoff frequencysufficiently lower than the above-described frequency f0. It convertsthe output signal of the detector 225 to a direct current (DC) signaland sends it out to the sample/hold circuit 227. The sample/hold circuit227 holds the output signal of the low-pass filter 226 and sends it outto the A/D (analog to digital) conversion circuit 228. The A/Dconversion circuit 228 converts the analog output of the sample/holdcircuit 227 to a digital signal and outputs it to the processingcontroller 233.

The coherent detector 229 performs coherent detection of the outputsignal of the receiving amplifier 224 with an AC signal from theoscillator 221 and sends out a signal having the level depending on thephase difference between them to the low-pass filter 230. This low-passfilter 230 has a cutoff frequency sufficiently lower than the frequencyf0. It converts the output signal of the coherent detector 229 to a DCsignal and sends it out to the sample/hold circuit 231. This sample/holdcircuit 231 holds the output signal of the low-pass filter 230 and sendsit out to the A/D (analog to digital) conversion circuit 232. The A/Dconversion circuit 232 converts the analog output of the sample/holdcircuit 231 to a digital signal and outputs it to the processingcontroller 233.

The processing controller 233 controls the respective units of theposition detecting device 202. Specifically, the processing controller233 controls selection of the loop coil in the selection circuit 213,switching of the switch connection circuit 223, and the timing of thesample/hold circuits 227 and 231. Based on the input signals from theA/D conversion circuits 228 and 232, the processing controller 233transmits radio waves from the X-axis-direction loop coils 211 and theY-axis-direction loop coils 212 for a certain transmission continuationtime.

An induced voltage is generated in the X-axis-direction loop coils 211and the Y-axis-direction loop coils 212 by radio waves transmitted fromthe position indicator 100. The processing controller 233 calculates thecoordinate values of the indicated position by the position indicator100 along the X-axis direction and the Y-axis direction based on thelevel of the voltage value of this induced voltage generated in therespective loop coils. Furthermore, the processing controller 233detects whether or not the push switch 118 is operated based on thelevel of the signal depending on the phase difference between thetransmitted radio waves and the received radio waves.

In this manner, in the position detecting device 202, the position ofthe position indicator 100 that has come close to the position detectingdevice 202 can be detected by the processing controller 233. Inaddition, the processing controller 233 of the position detecting device202 detects the shift of the phase (frequency) of the received signal.Thereby, it can detect the writing pressure applied to the core body ofthe position indicator 100 and can detect whether or not the push switch118 is turned on in the position indicator 100.

In the above-described manner, the position detecting device 202 candetect the writing pressure and operation of the push switch 118 bydetecting the frequency shift of the resonant frequency (phase) of theresonant circuit of the position indicator 100.

PRIOR ART DOCUMENT Patent Document

[Patent Document 1]

-   Japanese Patent Laid-open No. 2002-244806

BRIEF SUMMARY Problems to be Solved by the Invention

As described above, in the related-art position indicator, one or pluralcapacitors are connected to the resonant circuit and fine adjustment isperformed by a trimmer capacitor in order to correct variation in theresonant frequency of the resonant circuit due to variation in theinductance value of the coil and variation in the capacitance value ofthe capacitor itself.

This causes the following problems. Specifically, plural capacitors areneeded to adjust the resonant frequency of the resonant circuit of theposition indicator and the cost is increased corresponding to the numberof these plural capacitors. In addition, it takes a lot of labor toconnect the capacitor to the resonant circuit by a jumper line.Furthermore, there is a problem that the space to dispose the pluralcapacitors is necessary and the size of the position indicatorincreases. In particular, the trimmer capacitor for fine adjustment ofthe resonant frequency of the resonant circuit of the position indicatoris an electronic component having a comparatively large shape and itscomponent cost is also high.

Furthermore, in the case of the position indicator including the pushswitch as a switch circuit, the resonant frequencies when the pushswitch is in the on-state and when it is in the off-state need to beadjusted by different capacitor groups and the cost increasescorresponding to this. In addition, there is also a problem that theplace to dispose the capacitor groups needs to be ensured.

According to one aspect of this invention, a capacitor is provided thatcan avoid the above-described problems and allows adjustment of thecapacitance value.

Means for Solving the Problems

To solve the above-described problems, this invention provides acapacitor including a dielectric film, a first conductor layer and asecond conductor layer which are disposed opposed to each other with theintermediary of the dielectric film and are wound into a rod shape, afirst electrode led out from the first conductor layer, and a secondelectrode led out from the second conductor layer.

In the capacitor, a first area-changeable conductor pattern for allowingchange in the conductor area of at least one conductor layer of thefirst conductor layer and the second conductor layer disposed on theouter circumference side of the capacitor wound into the rod shape isformed in the conductor layer in such a manner as to be capable of beingsubjected to physical treatment from outside, and the capacitor has avalue of capacitance corresponding to the change in the conductor areaof the conductor layer.

According to the capacitor with the above-described configuration, bygiving physical treatment of, for example, dividing or connecting thefirst area-changeable conductor pattern from outside in the capacitorwound into the rod shape, the conductor area of the conductor layer inwhich this first area-changeable conductor pattern is formed can bechanged. Therefore, according to the capacitor by this invention, bygiving physical treatment to the first area-changeable conductor patternfrom outside, adjustment can be readily performed to make the capacitorhave such a capacitance value as to permit the resonant frequency of aresonant circuit to be set to the desired frequency, for example.

Effect of the Invention

According to this invention, by giving physical treatment to the firstarea-changeable conductor pattern from outside, the desired capacitancevalue can be easily set for the capacitor. Therefore, if the capacitoraccording to this invention is used for, for example, theabove-described resonant circuit and tuned circuit, the resonantfrequency and the tuning frequency can be optimized by the singlecapacitor.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1A to 1C are diagrams for explaining a configuration example of afirst embodiment of a capacitor according to this invention.

FIG. 2 is a diagram for explaining the configuration example of thefirst embodiment of the capacitor according to this invention.

FIG. 3 is a diagram for explaining the configuration example of thefirst embodiment of the capacitor according to this invention.

FIG. 4 is a diagram for explaining the configuration example of thefirst embodiment of the capacitor according to this invention.

FIG. 5 is a diagram showing an equivalent circuit example of the firstembodiment of the capacitor according to this invention.

FIG. 6 is a diagram showing an application example of the firstembodiment of the capacitor according to this invention.

FIGS. 7A to 7C are diagrams for explaining the application example ofthe first embodiment of the capacitor according to this invention.

FIGS. 8A to 8E are diagrams for explaining the application example ofthe first embodiment of the capacitor according to this invention.

FIGS. 9A to 9C are diagrams for explaining a configuration example of asecond embodiment of the capacitor according to this invention.

FIGS. 10A to 10C are diagrams for explaining the configuration exampleof the second embodiment of the capacitor according to this invention.

FIG. 11 is a diagram showing an equivalent circuit example of the secondembodiment of the capacitor according to this invention.

FIG. 12 is a diagram showing another application example of theembodiments of the capacitor according to this invention.

FIGS. 13A to 13D are diagrams for explaining another application exampleof the embodiments of the capacitor according to this invention.

FIG. 14 is a diagram showing an equivalent circuit example of anotherapplication example of the embodiments of the capacitor according tothis invention.

FIG. 15 is a diagram showing yet another application example of theembodiments of the capacitor according to this invention.

FIGS. 16A and 16B are diagrams for explaining yet another applicationexample of the embodiments of the capacitor according to this invention.

FIGS. 17A to 17C are diagrams for explaining yet another applicationexample of the embodiments of the capacitor according to this invention.

FIGS. 18A and 18B are diagrams showing a configuration example ofanother embodiment of the capacitor according to this invention.

FIG. 19 is a diagram showing a configuration example of anotherembodiment of the capacitor according to this invention.

FIGS. 20A to 20C are diagrams showing a configuration example of anotherembodiment of the capacitor according to this invention.

FIGS. 21A and 21B are diagrams showing a configuration example ofanother embodiment of the capacitor according to this invention.

FIGS. 22A to 22C are diagrams showing a configuration example of anotherembodiment of the capacitor according to this invention.

FIGS. 23A to 23D are diagrams showing a configuration example of anotherembodiment of the capacitor according to this invention.

FIG. 24 is a diagram showing a configuration example of one example of arelated-art position indicator.

FIG. 25 is a diagram for explaining the configuration example of oneexample of the related-art position indicator.

DETAILED DESCRIPTION First Embodiment

FIGS. 1A to 4 are diagrams for explaining a configuration example of afirst embodiment of the capacitor according to this invention. Acapacitor 1 of this first embodiment is based on the supposition that itis used as a capacitor configuring a resonant circuit of a positionindicator that has the above-described pen shape and includes theabove-described push switch as a switch circuit.

The capacitor 1 of this first embodiment is a so-called film capacitor.The film capacitor 1 is obtained by winding a film capacitor 5, which isobtained by forming a first conductor layer 3 and a second conductorlayer 4 disposed opposed to each other with the intermediary of adielectric film 2 on the front and back surfaces of this dielectric film2 by, for example, evaporation as shown in FIGS. 1A to 1C, and aninsulating film 6 shown in FIG. 2, as shown in FIG. 3, so that thecapacitor 1 is configured as a rod-shaped component like that shown inFIG. 4. In the example of the diagram, the horizontal direction of thedielectric film 2 that is long in the horizontal direction is defined asthe axial core direction of the winding and the vertical direction ofthe dielectric film 2 is defined as the winding direction. However, thisis for convenience of explanation. For example, the horizontal directionof the dielectric film 2 that is long in the vertical direction may bedefined as the axial core direction of the winding, of course.

The dielectric film 2 and the insulating film 6 are formed of adielectric such as polyethylene terephthalate (PET), polypropylene,polyethylene naphthalate, polyphenylene sulfide, or polycarbonate. Thefirst conductor layer 3 and the second conductor layer 4 are formed of,for example, a metal layer of aluminum, zinc, or an alloy of them andare formed on the dielectric film 2 by metal evaporation.

FIG. 1B shows the side of a back surface 2 b of the dielectric film 2,and the second conductor layer 4 is formed across almost the entiresurface thereof. FIG. 1A shows the side of a front surface 2 a of thedielectric film 2, and the first conductor layer 3 formed of a conductorpattern to be subjected to physical treatment from outside to change itsconductor area. Therefore, the film capacitor 5, in which the firstconductor layer 3 and the second conductor layer 4 are formed opposed toeach other with the intermediary of the dielectric film 2, hascapacitance depending on the conductor area of the first conductor layer3 that changes the conductor area due to physical treatment fromoutside, such as division treatment or connection treatment of theconductor pattern. FIG. 1B shows the state in which the dielectric film2 of FIG. 1A is turned over with its upper and lower ends reversed, andthe left and right ends of the dielectric film 2 are the same betweenFIGS. 1A and 1B.

In this first embodiment, as shown in FIG. 1A, the conductor pattern ofthe first conductor layer 3 is composed of first and second commonconductor patterns 31 a and 31 b, one or more, specifically seven inthis example, capacitance-forming conductor patterns 32 a, 32 b, 32 c,32 d, 32 e, 32 f, and 32 g, and area-changeable conductor patterns 33 a,33 b, 33 c, 33 d, 33 e, 33 f, and 33 g whose number corresponds to thenumber of capacitance-forming conductor patterns 32 a to 32 g.

The area-changeable conductor patterns 33 a to 33 d are formed betweenthe first common conductor pattern 31 a and the capacitance-formingconductor patterns 32 a to 32 d, respectively. The area-changeableconductor patterns 33 e to 33 g are formed between the second commonconductor pattern 31 b and the capacitance-forming conductor patterns 32e to 32 g, respectively. Furthermore, the area-changeable conductorpatterns 33 a to 33 g are formed at positions on the outer circumferenceside of the wound part of the rod-shaped capacitor 1, preferably on theoutermost circumferential surface side, so that they can be subjected tophysical treatment in the rod-shaped capacitor 1 after the capacitor 1is made as a completed component.

In this first embodiment, the area-changeable conductor patterns 33 a to33 g include axially-disposed conductor patterns 34 a, 34 b, 34 c, 34 d,34 e, 34 f, and 34 g, respectively, extended along the axial coredirection of the capacitor 1 formed by being wound into a rod shape.After the capacitor 1 is made as the completed component, theseaxially-disposed conductor patterns 34 a to 34 g are physically divided,corresponding to the desired capacitance value in the rod-shapedcapacitor 1, along the direction perpendicular to the extensiondirection thereof (i.e., circumferential direction of the capacitor 1),as shown by the dotted line in FIG. 1A. Thereby, the capacitance-formingconductor patterns 32 a to 32 d and the first common conductor pattern31 a, and the capacitance-forming conductor patterns 32 e to 32 g andthe second common conductor pattern 31 b are each set to a state ofbeing electrically disconnected or connected. Thus, the conductor areaof the first conductor layer 3 forming the capacitance of the capacitor1 is changed.

Furthermore, in this example, as shown in FIG. 1A, the axially-disposedconductor patterns 34 a to 34 g configuring the area-changeableconductor patterns 33 a to 33 g are disposed at positions separate fromthe winding-finish end of the winding direction of the dielectric film 2by a predetermined distance d in such a manner as to be arranged in onerow and at equal intervals along the horizontal direction of thedielectric film 2, i.e., the axial core direction of the capacitor 1. Asa result, in the rod-shaped capacitor 1, the axially-disposed conductorpatterns 34 a to 34 g configuring the area-changeable conductor patterns33 a to 33 g are disposed at the same position in the circumferentialdirection of the capacitor 1 in such a manner as to be arranged in onerow along the axial core direction of the capacitor 1. In this case, thepredetermined distance d is so selected as to satisfy d<2πr when theradius of the capacitor 1 of this example wound into a rod shape asshown in FIG. 4 is defined as r so that all of the axially-disposedconductor patterns 34 a to 34 g may be located at the outermostcircumferential part of the rod-shaped capacitor 1.

Moreover, in this example, each of the axially-disposed conductorpatterns 34 a to 34 g configuring the area-changeable conductor patterns33 a to 33 g is so formed that each of the capacitance-forming conductorpatterns 32 a to 32 g can be individually separated from the firstcommon conductor pattern 31 a or the second common conductor pattern 31b.

Each of the capacitance-forming conductor patterns 32 a to 32 g isformed as a strip-shaped conductor pattern in this example. The widths(lengths in the horizontal direction of the dielectric film 2) W of theconductor patterns are so selected as to be equal to each other. Inaddition, the conductor patterns are so formed that the lengths in thewinding direction of the capacitor 1 are different from each other asshown in FIG. 1A. Therefore, each of the capacitance-forming conductorpatterns 32 a to 32 g is formed as a conductor region with a differentarea. Furthermore, an insulating part is formed among thecapacitance-forming conductor patterns 32 a to 32 g except for the partsof the area-changeable conductor patterns 33 a to 33 g.

As described above, the second conductor layer 4 is uniformly formed onthe side of the back surface 2 b of the dielectric film 2. Thus, each ofthe capacitance-forming conductor patterns 32 a to 32 g is opposed tothe second conductor layer 4 with the intermediary of the dielectricfilm 2 to thereby form a capacitor with capacitance according to itsarea.

As shown in FIG. 1B, in the second conductor layer 4 on the side of theback surface 2 b of the dielectric film 2, non-conductor regions 41 a to41 g are defined, in which the conductor layer 4 is not formed, at thepositions corresponding to the positions of the axially-disposedconductor patterns 34 a to 34 g, which are possibly divided (severed) inthe area-changeable conductor patterns 33 a to 33 g of the firstconductor layer 3 on the side of the front surface 2 a after thecapacitor 1 is completed. The reason why these non-conductor regions 41a to 41 g are set is as follows. Specifically, when division of theconductor layer is performed in the axially-disposed conductor patterns34 a to 34 g forming the area-changeable conductor patterns 33 a to 33g, electrical connection of the conductor layer 3 on the side of thefront surface 2 a to the conductor layer 4 on the side of the backsurface 2 b possibly occurs in association with the division treatmentif the conductor layer 4 exists at the respective positions on the sideof the back surface 2 b corresponding to the axially-disposed conductorpatterns 34 a to 34 g. Therefore, the non-conductor regions 41 a to 41 gare set in order to prevent the occurrence of such a situation.

The first common conductor pattern 31 a is formed across most of theremaining region outside the capacitance-forming conductor patterns 32 ato 32 g on the front surface 2 a of the dielectric film 2. Furthermore,in this example, the capacitance-forming conductor patterns 32 a to 32 damong the plural capacitance-forming conductor patterns 32 a to 32 g aretreated as a first group and are coupled to the first common conductorpattern 31 a via their respective area-changeable conductor patterns 33a to 33 d. This first common conductor pattern 31 a is also opposed tothe second conductor layer 4 on the side of the back surface 2 b withthe intermediary of the dielectric film 2 and forms a capacitance valuedepending on its area.

The capacitance-forming conductor patterns 32 e to 32 g among the pluralcapacitance-forming conductor patterns 32 a to 32 g are treated as asecond group and are coupled to the second common conductor pattern 31 bvia their respective area-changeable conductor patterns 33 e to 33 g.

In this example, circular projections 21 and 22 are formed in thedielectric film 2. When the dielectric film 2 is wound into a rod shapeto be configured as the capacitor 1, the circular projections 21 and 22serve as lid parts at both ends in the winding axial core direction.These circular projections 21 and 22 are regions utilized as electrodelead-out parts of the capacitor 1 of this example in the dielectric film2. In this example, they are formed at positions on the winding-finishend side when the dielectric film 2 is wound into a rod shape and atboth left and right ends in the axial core direction.

Furthermore, in the capacitor 1 of this first embodiment, a ring-shapedelectrode conductor 35 is formed on the circular projection 21 as shownin FIG. 1A. This ring-shaped electrode conductor 35 is extended from thefirst common conductor pattern 31 a coupled to the capacitance-formingconductor patterns 32 a to 32 d of the first group, in the firstconductor layer 3 formed on the front surface 2 a of the dielectric film2.

On the circular projection 22, a substantially-half-ring-shapedelectrode conductor 36 extended from the second common conductor pattern31 b coupled to the capacitance-forming conductor patterns 32 e to 32 gof the second group is formed. In addition, asubstantially-half-ring-shaped electrode conductor 37 extended from thefirst common conductor pattern 31 a is formed. These conductors 36 and37 are not connected to each other.

Moreover, in the capacitor 1 of this first embodiment, as shown in FIGS.1B and 3, the dielectric film 2 is wound together with the insulatingfilm 6 with use of an axial core conductor 7 formed of a metal conductorof e.g., copper or aluminum as the center axial core. By using thisaxial core conductor 7, an electrode of the capacitor is led out fromthe second conductor layer 4 formed on the back surface 2 b of thedielectric film 2. That is, the axial core conductor 7 ispressure-bonded and electrically connected to the second conductor layer4 as shown by the dotted line in FIG. 1B. The length of this axial coreconductor 7 is so selected as to be slightly larger than the horizontalwidth of the dielectric film 2 so that the axial core conductor 7 mayproject from both ends in the winding axial core direction.

At the center part of the circular projections 21 and 22 of thedielectric film 2, penetration holes 21 a and 22 a are formed, throughwhich both ends of the axial core conductor 7 penetrate so that theaxial core conductor 7 may be projected and exposed to the external. Aninsulating region, in which no conductor layer is formed, is formedbetween the penetration hole 21 a and the ring-shaped conductor 35 sothat the axial core conductor 7 may be electrically insulated from thering-shaped conductor 35. Similarly, an insulating region, in which noconductor layer is formed, is formed between the penetration hole 22 aand the substantially-half-ring-shaped conductors 36 and 37 so that theaxial core conductor 7 may be electrically insulated from thesubstantially-half-ring-shaped conductors 36 and 37.

When the dielectric film 2 and the insulating film 6 are wound and therod-shaped capacitor 1 is formed as shown in FIG. 3, for example anadhesive is applied to the respective end surfaces in the axial coredirection of this rod-shaped capacitor 1 to thereby seal the capacitor 1and ensure quality of the moisture resistance and so forth. In addition,the circular projections 21 and 22 are bent toward the respective endsurface sides so that both end parts of the axial core conductor 7penetrating through the penetration holes 21 a and 22 a of the circularprojections 21 and 22 may be projected to the external. The circularprojections 21 and 22 are fixed to the respective end surfaces by theapplied adhesive. Furthermore, adhesive-applied parts 21 b and 22 bformed as extensions of the circular projections 21 and 22,respectively, are fixed to the circumferential side surface of therod-shaped body by an adhesive or the like. Due to this, electrodes ofthe capacitor are disposed on the circular projections 21 and 22, andthe circular projections 21 and 22 function as lid parts for the windingend surfaces of the capacitor 1.

If the dielectric film 2 is wound as it is, the first conductor layer 3and the second conductor layer 4 on the front and back surfaces thereofare electrically connected to each other. To prevent this, in thisexample, the insulating film 6 is overlapped on the side of the frontsurface 2 a of the dielectric film 2 to be wound as shown in FIG. 3, sothat the capacitor 1 is configured. The insulating film 6 is formed of aplain dielectric film on which no conductor is formed.

Furthermore, as shown in FIG. 2, on the winding-finish end side of theinsulating film 6 and on the side of a surface 6 a exposed to theexternal after the winding finish, division marks 61 a to 61 g areformed by, for example, printing, and are displayed at the positionsthat correspond to the respective positions of the axially-disposedconductor patterns 34 a to 34 g configuring the area-changeableconductor patterns 33 a to 33 g formed in the first conductor layer 3 onthe dielectric film 2 when the insulating film 6 is overlapped on thedielectric film 2 and wound as shown in FIG. 3.

Moreover, as shown in FIG. 2, near the respective division marks 61 a to61 g, capacitance values corresponding to the respective areas of thecapacitance-forming conductor patterns 32 a to 32 g, which areelectrically disconnected and separated when division is performed atthe positions of the axially-disposed conductor patterns 34 a to 34 gconfiguring the area-changeable conductor patterns 33 a to 33 g,respectively, are marked by, for example, printing.

When the film capacitor 5 and the insulating film 6 are wound around theaxial core conductor 7 as the axial core as shown in FIG. 3, thesedivision marks 61 a to 61 g and the printed capacitance values areexposed to the outermost circumferential surface of the rod-shapedcapacitor 1 as shown in FIG. 4.

As shown in FIG. 1A, the axially-disposed conductor patterns 34 a to 34g configuring the area-changeable conductor patterns 33 a to 33 g areformed at the same position in the circumferential direction of therod-shaped capacitor 1 in such a manner as to be arranged in one row atequal intervals along the axial core direction of the rod-shapedcapacitor 1. Therefore, the division marks 61 a to 61 g and thecapacitance values are arranged in one row at equal intervals along theaxial core direction of the rod-shaped capacitor 1 as shown in FIG. 4.

Furthermore, as shown in FIG. 2, circumferential position marks 62 a and62 b and a segment mark 63 linking these marks 62 a and 62 b are formedby, for example, printing, and are displayed on the insulating film 6 inorder to indicate the circumferential position of the axially-disposedconductor patterns 34 a to 34 g configuring the area-changeableconductor patterns 33 a to 33 g.

Moreover, on the insulating film 6, axial core direction marks 64 a to64 g are each formed by, for example, printing, and are displayed at thesame position in the axial core direction as that of a respective one ofthe division marks 61 a to 61 g and at a position shifted from therespective one of the division marks 61 a to 61 g by a predeterminedlength along the circumferential direction of the rod-shaped capacitor1.

Therefore, although the axially-disposed conductor patterns 34 a to 34 gconfiguring the area-changeable conductor patterns 33 a to 33 g of thefilm capacitor 5 configured with the first conductor layer 3 and thesecond conductor layer 4 opposed to each other with the intermediary ofthe dielectric film 2 are hidden because of the winding of theinsulating film 6, division at the area-changeable conductor patterns 33a to 33 g can be performed accurately and surely by performing divisiontreatment with the help of all or part of the division marks 61 a to 61g, the circumferential position marks 62 a and 62 b, the segment mark63, the axial core direction marks 64 a to 64 g, and the numerical valuedisplay of the capacitance values.

The adjustment of the capacitance value of the capacitor 1 may bemanually performed by an adjuster person. However, for example, it isalso possible to perform division treatment by an automatic machine inthe following manner with the help of all or part of the division marks61 a to 61 g, the circumferential position marks 62 a and 62 b, thesegment mark 63, the axial core direction marks 64 a to 64 g, and thenumerical value display of the capacitance values.

In this case, the capacitor 1 is so attached that it can be rotatedabout the axial core conductor 7 as the rotational center axis.Furthermore, a camera for photographing the circumferential side surfaceof the capacitor 1 and capturing its image is provided. In addition, adivision measure formed of a cutter or the like is provided for dividingthe axially-disposed conductor patterns 34 a to 34 g configuring thearea-changeable conductor patterns 33 a to 33 g with the help of themarks such as the division marks 61 a to 61 g.

First, the capacitance value that should be set in the capacitor 1 afteradjustment is obtained in advance and the axially-disposed conductorpattern that should be divided to yield this capacitance value issettled among the axially-disposed conductor patterns 34 a to 34 g.

Next, the capacitor 1 is rotated about the axial core conductor 7 as therotational center axis while the image of the circumferential sidesurface of the capacitor 1 is captured by the camera. Then, thecircumferential position at which the axially-disposed conductorpatterns 34 a to 34 g can be divided by the division measure is obtainedwith the help of the circumferential position marks 62 a and 62 b andthe segment mark 63, and the rotation is stopped at this position.

Next, the axial core direction position of the division measure relativeto the capacitor 1 is decided with the help of the axial core directionmarks 64 a to 64 g and the division marks 61 a to 61 g. Then, theposition control of the division measure is carried out to divide onlythe predefined axially-disposed conductor pattern that should bedivided. Then, the capacitor 1 is rotated about the axial core conductor7 in such a manner that the axial core direction marks 64 a to 64 g arefollowed by the division marks 61 a to 61 g along the circumferentialdirection, for example, and division of the predefined axially-disposedconductor pattern that should be divided is performed by the divisionmeasure. In this division, the capacitance value decreased by thedivision of the axially-disposed conductor pattern that should bedivided can be visually confirmed based on the printed numerical value.The divided part is sealed by a resin material or the like to maintainquality of the moisture resistance and so forth.

The above-described division by the division measure is performed fromthe side of the surface 6 a of the insulating film 6 in FIG. 3. In thisexample, in order to prevent this division from extending to the woundpart underneath the axially-disposed conductor patterns 64 a to 64 g, adivision block sheet 65 having a predetermined length D is formed bydeposition near the winding-finish end of the surface 2 b of thedielectric film 2 configuring the film capacitor 5 corresponding to thepositions at which the axially-disposed conductor patterns are disposedas shown in FIG. 3.

Although a component separate from the insulating film 6 is provided asthe division block sheet 65 in the example of FIG. 3, the following waymay be employed. Specifically, the insulating film 6 is extended to belonger than the film capacitor 5 by a length D. This extended part ofthe insulating film 6 with the length D is folded back from thewinding-finish end of the film capacitor 5 to cover the winding-finishend side of the surface 2 b of the dielectric film 2. Thereby, thisfolded part is made to play the same role as that of the division blocksheet 65. Alternatively, the dielectric film 2 itself may be extended bythe length corresponding to the division block sheet and this extendedpart may be folded back.

As shown in FIG. 4, ring-shaped projections 66 and 67 are formed nearboth ends in the axial core direction of the rod-shaped capacitor 1.These ring-shaped projections 66 and 67 are to lock the capacitor 1 ofthe above-described first embodiment by fitting it into coupling membersto be described later, which is used when the capacitor 1 is coupled tothe ferrite core and so forth.

At the axial end part of the rod-shaped capacitor 1 on the side oppositeto the end part at which the electrode conductor 35 is formed, an axialcore direction projection 68 for restricting the circumferentialposition when the capacitor 1 is fitted into the coupling member to bedescribed later is formed. The axial core direction projection 68 isformed from a predetermined circumferential position at the ring-shapedprojection 67 along the axial core direction to the axial end part atwhich the electrode conductors 36 and 37 (not shown in FIG. 4) areformed.

These projections 66 and 67 can be formed by inserting a linear memberalong the winding direction when the film capacitor 5 and the insulatingfilm 6 are wound into a rod shape. The projection 68 can be formed byinserting a linear member along the direction perpendicular to thewinding direction when the film capacitor 5 and the insulating film 6are wound into a rod shape.

[Equivalent Circuit of Capacitor 1]

The equivalent circuit of the capacitor 1 of the first embodiment withthe above-described configuration is shown in FIG. 5 and is surroundedby the dotted line. In this FIG. 5, conceptually Co1 and Co2 arecapacitances that are formed by opposing of the first common conductorpattern 31 a and the second common conductor pattern 31 b of the firstconductor layer 3, respectively, to the second conductor layer 4 withthe intermediary of the dielectric film 2 and that are according totheir respective areas. Ca to Cg are capacitances that are formed byopposing of the capacitance-forming conductor patterns 32 a to 32 g ofthe first conductor layer 3, respectively, to the second conductor layer4 with the intermediary of the dielectric film 2 and that are accordingto their respective areas.

The second conductor layer 4 on the side of the back surface 2 b of thedielectric film 2 serves as one electrode (common electrode) of thecapacitor configuring the capacitances Co1, Co2, and Ca to Cg, and thiscommon electrode is led out from the axial core conductor 7.Furthermore, as shown in FIG. 1A, the ring-shaped electrode conductor 35on the circular projection 21 is connected to the first common conductorpattern 31 a of the conductor layer 3 formed on the front surface 2 a ofthe dielectric film 2. Thus, the ring-shaped electrode conductor 35serves as the other electrode of the capacitor configuring thecapacitance Co1 and the capacitances Ca to Cd, corresponding to theareas of the first common conductor pattern 31 a and thecapacitance-forming conductor patterns 32 a to 32 d of the first groupamong the capacitance-forming conductor patterns 32 a to 32 g.

The electrode conductor 35 is connected to the electrode conductor 37via the first common conductor pattern 31 a. Furthermore, the electrodeconductor 36 is connected to the second common conductor pattern 31 b.Thus, the electrode conductor 36 serves as the other electrode of thecapacitor configuring the capacitance Co2 and the capacitances Ce to Cg,corresponding to the areas of the second common conductor pattern 31 band the capacitance-forming conductor patterns 32 e to 32 g of thesecond group among the capacitance-forming conductor patterns 32 a to 32g.

Therefore, as shown in FIG. 5, the capacitance Co1 according to the areaof the first common conductor pattern 31 a and the capacitances Ca to Cdaccording to the areas of the capacitance-forming conductor patterns 32a to 32 d are connected in parallel to each other between the axial coreconductor 7, which is the electrode connected to the second conductorlayer 4, and the ring-shaped electrode conductor 35.

When any of the axially-disposed conductor patterns 34 a to 34 dconfiguring the area-changeable conductor patterns 33 a to 33 d isdivided as described above, this divided capacitance among thecapacitances Ca to Cd connected in parallel to the capacitor Co1 is cutat the position indicated by the dotted line in FIG. 5 to becomedisconnected. Thus, the capacitance between the axial core conductor 7as the electrode and the ring-shaped electrode conductor 35 decreases bythis disconnected capacitance.

When the electrode conductor 36 is electrically connected to theelectrode conductor 37, the capacitances Co1 and Co2 according to theareas of the first common conductor pattern 31 a and the second commonconductor pattern 31 b and the capacitances Ca to Cg according to theareas of the capacitance-forming conductor patterns 32 a to 32 g areconnected in parallel to each other between the axial core conductor 7,which is the electrode connected to the second conductor layer 4, andthe ring-shaped electrode conductor 35.

When any of the axially-disposed conductor patterns 34 e to 34 gconfiguring the area-changeable conductor patterns 33 e to 33 g isdivided, this divided capacitance among the capacitances Ce to Cgconnected in parallel to the capacitor Co2 is cut at the positionindicated by the dotted line in FIG. 5 to become disconnected. Thus, thecapacitance of the capacitor 1 decreases by this disconnectedcapacitance.

[Example of Adjustment Method of Resonant Frequency by Adjustment ofCapacitance of Capacitor 1]

Therefore, for example, when this capacitor 1 is used as the capacitorconfiguring the resonant circuit of the position indicator for theabove-described position detecting device of the electromagneticinduction system, the resonant frequency of the resonant circuit can beadjusted by adjusting the capacitance of this capacitor 1 as describedbelow.

Specifically, the coil 105 is connected between the axial core conductor7 serving as one electrode of the capacitor 1 and the ring-shapedelectrode conductor 35 serving as the other electrode of the capacitor1, to configure a parallel resonant circuit with the capacitances Co1,Co2, and Ca to Cg of the capacitor 1. In addition, in this example, apush switch 118A as a switch circuit is connected between the electrodeconductor 36 and the electrode conductor 37 in advance as describedlater. In this case, the inductance value of the coil 105 when thewriting pressure is zero for example is measured to be acquired inadvance.

When the push switch 118A is in the off-state or the push switch 118A isin the non-connected state, i.e., when the electrode conductor 36 is notconnected to the electrode conductor 37, the capacitances Co2 and Ce toCg are isolated from the capacitor 1. In order for the resonantfrequency at this time to be a first value, the capacitance that shouldbe connected in parallel to the coil 105 is obtained. Next, thenecessary patterns among the axially-disposed conductor patterns 34 a to34 d configuring the area-changeable conductor patterns 33 a to 33 d aresubjected to division treatment so that this obtained capacitance may berealized.

Next, when the push switch 118A is in the on-state, i.e., when theelectrode conductor 36 is short-circuited to the electrode conductor 37,the capacitances Co2 and Ce to Cg are added to the capacitor 1. In orderfor the resonant frequency at this time to be a second value, thecapacitance that should be connected in parallel to the coil 105 isobtained. Next, the necessary patterns among the axially-disposedconductor patterns 34 e to 34 g configuring the area-changeableconductor patterns 33 e to 33 g are subjected to division treatment sothat this obtained capacitance may be realized.

In the above description, the capacitor 1 is used for adjustment of theresonant frequency of the resonant circuit in the position indicatorsimilar to the position indicator 100 that has a configuration includingthe push switch 118A and is used together with the position detectingdevice of the electromagnetic induction system. Therefore, theconfiguration in which the push switch 118A is connected between theelectrode conductor 36 and the electrode conductor 37 is employed.

However, the capacitor 1 of this invention can be used also in the caseof adjusting the resonant frequency of the resonant circuit in aposition indicator that does not have a push switch (or side switch) asa switch circuit and is used together with the position detecting deviceof the electromagnetic induction system. In this case, a configurationmay be employed in which the electrode conductor 36 is notshort-circuited to the electrode conductor 37 and the capacitances Co2and Ce to Cg are not used. However, it is possible to short-circuit theelectrode conductor 36 to the electrode conductor 37 and selectively useall of the capacitances Co1, Co2, and Ca to Cg of the capacitor 1 asparallel capacitance configuring the resonant circuit. That is, it ispossible to provide, with only one capacitor 1, operation and effectsequivalent to those provided by a large number of capacitors includingthe existing trimmer capacitor.

[Example of Position Indicator Including Capacitor 1 of FirstEmbodiment]

FIG. 6 shows a configuration example of a position indicator 100A usingthe capacitor 1 of the above-described first embodiment as the capacitorconfiguring the resonant circuit. The position indicator 100A of theexample of this FIG. 6 is an example of the position indicator usedtogether with the position detecting device of the electromagneticinduction system shown in FIG. 25. The same respective components asthose in the position indicator 100 of the example of FIG. 24 are giventhe same reference numerals and detailed description thereof is omitted.In FIG. 6, a case 111A is shown in cross-section for easy explanation ofthe configuration within the case 111A.

As shown in FIG. 6, in the position indicator 100A of this example, thecase 111A is composed of a hollow cylindrical outside case 111Aa and aninside case 111Ab and has a configuration in which the outside case111Aa is concentrically fitted to the inside case 111Ab. In the hollowpart of the case 111A, members for writing pressure detection, thecapacitor 1 of the first embodiment, and the push switch 118A are sohoused as to be sequentially arranged along the center line direction ofthe case 111A.

The push switch 118A used in this example has a columnar chassis shapeand a pressing part 118Ap is exposed at the circumferential side surfaceof this columnar chassis. This pressing part 118Ap is pressed by afinger to thereby turn on/off the switch provided inside the chassis.Furthermore, although not shown in the diagram, a penetration hole thatpenetrates the outside case 111Aa and the inside case 111Ab and allowsthe pressing operation part 118Ap of the push switch 118A to be seenfrom outside is made in the case 111A. Furthermore, at this penetrationhole part of the case 111A, a pressing operation element (not shown) topress the pressing operation part 118Ap of the push switch 118A is soprovided as to permit pressing operation from outside.

In this example, the members for writing pressure detection have thesame configuration as that of the above-described position indicator100. Specifically, as shown in FIG. 6, similarly to the above-describedposition indicator 100, the position indicator 100A of this exampleincludes the coil 105, which is one example of an inductance element andis wound around the ferrite core 104, which is one example of a magneticbody, and the ferrite chip 102 opposed to the ferrite core 104 with theintermediary of the O-ring 103 formed of an elastic member. The positionindicator 100A has a configuration in which the inductance value of thecoil 105 changes depending on the writing pressure applied to the corebody 101. The outside case 111Aa has an opening 111Ac for allowing thecore body 101 to be projected from the tip part of the positionindicator 100A.

In this example, the part of the ferrite core 104 on the opposite sideto the core body 101 is coupled to the rod-shaped capacitor 1 by acoupling member 8A. Furthermore, the capacitor 1 is coupled to the pushswitch 118A by a coupling member 9A. The coupling member 8Amechanistically couples the ferrite core 104 to the capacitor 1 and alsoelectrically connects one end and the other end of the coil 105 woundaround the ferrite core 104 to the axial core conductor 7 and theelectrode conductor 35, respectively, serving as the electrodes of thecapacitor 1. Furthermore, the coupling member 9A mechanistically couplesthe capacitor 1 to the push switch 118A and also electrically connectsthe electrode conductor 36 and the electrode conductor 37 of thecapacitor 1 to one terminal and the other terminal, respectively, of thepush switch 118A.

FIGS. 7A to 7C are diagrams for explaining a configuration example ofthe coupling member 8A. FIG. 7A is a diagram when the coupling member 8Ais viewed from the side coupled to the ferrite core 104 and FIG. 7B is asectional view along line B-B in FIG. 7A. FIG. 7C is a diagram forexplaining how the capacitor 1 is coupled to the coupling member 8Acoupled to the ferrite core 104.

As shown in FIGS. 7A and 7B, the coupling member 8A is obtained byperforming insert molding in the following manner. Specifically, arecess 82 into which the capacitor 1 is fitted is formed in a main body81 formed of a columnar resin member. In addition, elastic terminalmembers 83 and 84 for electrically connecting one end 105 a and theother end 105 b of the coil 105 to the electrode conductor 35 and theaxial core conductor 7 of the capacitor 1 are inserted.

The recess 82 is a circular concave hole having an inner diameter almostequal to the outer diameter of the rod-shaped capacitor 1. A ring-shapedconcave trench 82 a is formed in the sidewall of this recess 82. Intothe ring-shaped concave trench 82 a, the ring-shaped projection 66provided at the end part of the rod-shaped capacitor 1 on the side onwhich the electrode conductor 35 is formed is fitted.

At the coupling part of the main body 81 to the ferrite core 104, aprojection 85 for positioning is formed at the center of a flat surface.On the other hand, the end surface of the ferrite core 104 on the sideof the coupling member 8A is a flat surface and a positioning recess 104a into which the projection 85 is fitted is formed at the centerthereof.

Furthermore, as shown in FIG. 7A, concave trenches 86 and 87 are formedalong the center line direction of the column at positions on thecircumferential side surface of the main body 81, specifically atpositions separate from each other by an angular distance of 180 degreesin this example. In these concave trenches 86 and 87, one end parts 83 aand 84 a of the terminal members 83 and 84 are vertically disposed alongthe direction perpendicular to the circumferential direction. In thesevertically-disposed one end parts 83 a and 84 a of the terminal members83 and 84, V-shaped notches 83 b and 84 b are formed as shown in FIG.7A.

In the state in which the projection 85 of the main body 81 of thecoupling member 8A is fitted into the recess 104 a formed in the endsurface of the ferrite core 104 as shown on the right side of FIG. 7C,the end surface of the ferrite core 104 is bonded to the flat surface ofthe main body 81 of the coupling member 8A by, for example, an adhesive.Furthermore, one end 105 a of the coil 105 is press-fitted into theV-shaped notch 83 b of one end part 83 a of the terminal member 83 andthey are electrically connected to each other. In addition, the otherend 105 b of the coil 105 is press-fitted into the V-shaped notch 84 bof one end part 84 a of the terminal member 84 and they are electricallyconnected to each other. The component that is shown on the right sideof this FIG. 7C and is obtained by coupling the coupling member 8A tothe ferrite core 104 around which the coil 105 is wound can be treatedas one ferrite core module.

In the coupling member 8A, the other end part 83 c of the terminalmember 83 is exposed from the bottom of the concave hole 82. Due tothis, as shown in FIG. 7C, the electrode conductor 35 of the capacitor 1is electrically connected to the terminal member 83 via the end part 83c when the rod-shaped capacitor 1 is inserted in the recess 82.

At the center of the bottom of the recess 82, a concave hole 82 b havinga diameter larger than that of the axial core conductor 7 of thecapacitor 1 is formed. The other end part 84 c of the terminal member 84is located in this concave hole 82 b. At the part, at which the otherend part 84 c of the terminal member 84 is located in this concave hole82 b, an insertion hole 84 d is formed, into which the axial coreconductor 7 of the capacitor 1 can be inserted. An elastic bent partformed in the terminal member 84 is disposed in the insertion hole 84 d.

Therefore, when the capacitor 1 is inserted in the recess 82, the axialcore conductor 7 of the capacitor 1 is inserted in the insertion hole 84d to get contact with the elastic bent part, so that the axial coreconductor 7 is electrically connected to the terminal member 84.Furthermore, the electrode conductor 35 of the capacitor 1 iselectrically connected to the other end part 83 c of the terminal member83. The ring-shaped projection 66 of the capacitor 1 is fitted into thering-shaped concave trench 82 a of the recess 82 of the coupling member8A and thereby the capacitor 1 is locked by the coupling member 8A. Inthe state in which the ferrite core 104 around which the coil 105 iswound is coupled to the capacitor 1 by the coupling member 8A in thismanner, the electrode conductor 35 and the axial core conductor 7 of thecapacitor 1 are connected to one end 105 a and the other end 105 b,respectively, of the coil 105. This provides the state in which the coil105 and the capacitor 1 are connected in parallel to each other.

Next, the coupling member 9A will be described. FIGS. 8A to 8E arediagrams for explaining a configuration example of this coupling member9A. FIG. 8A is a diagram when the coupling member 9A is viewed from theside coupled to the capacitor 1 and FIG. 8B is a sectional view alongline C-C in FIG. 8A. FIG. 8C is a diagram when the coupling member 9A isviewed from the side coupled to the push switch 118A. FIG. 8D is adiagram showing the end part of the capacitor 1 on the side coupled tothe coupling member 9A. FIG. 8E is a diagram showing the end part of thepush switch 118A on the side coupled to the coupling member 9A.

As shown in FIGS. 8A and 8B, the coupling member 9A is obtained byperforming insert molding in the following manner. Specifically, arecess 92 into which the capacitor 1 is fitted and a recess 93 intowhich the push switch 118A is fitted are formed in a main body 91 formedof a columnar resin member. In addition, elastic terminal members 94 and95 for electrically connecting the electrode conductors 36 and 37 of thecapacitor 1 to one and the other terminals of the push switch 118A areinserted.

In this case, the recess 92 is a circular concave hole having a diameteralmost equal to the outer diameter of the rod-shaped capacitor 1. In thesidewall of this recess 92, a ring-shaped concave trench 92 a and anaxial core direction concave trench 92 b are formed. The ring-shapedprojection 67 (see FIG. 8D) provided at the end part of the rod-shapedcapacitor 1 on the side on which the electrode conductors 36 and 37 areformed is fitted into the ring-shaped concave trench 92 a. The axialcore direction projection 68 (see FIG. 8D) formed in the capacitor 1 isengaged with the axial core direction concave trench 92 b. In the bottomsurface of this recess 92, a concave hole 96 into which the axial coreconductor 7 of the capacitor 1 is inserted is formed. Furthermore, oneend parts 94 a and 95 a of the terminal members 94 and 95 are exposed atthe bottom of this recess 92.

The recess 93 is a circular concave hole having a diameter almost equalto the outer diameter of the columnar push switch 118A. In the sidewallof this recess 93, a ring-shaped concave trench 93 a and an axial coredirection concave trench 93 b are formed. A ring-shaped projection 118Acprovided at the end part of the columnar push switch 118A on the side onwhich one terminal 118Aa and the other terminal 118Ab are formed asshown in FIG. 8E is fitted into the ring-shaped concave trench 93 a. Anaxial core direction projection 118Ad (see FIG. 8E) formed in the pushswitch 118A is engaged with the axial core direction concave trench 93b. Furthermore, the other end parts 94 b and 95 b of the terminalmembers 94 and 95 are exposed at the bottom of this recess 93.

The side of the capacitor 1, where the circular projection 22, on whichthe electrode conductors 36 and 37 shown in FIG. 8D are formed, formsthe end surface, is inserted into the recess 92 of the coupling member9A in the state in which alignment in the circumferential direction isachieved by the axial core direction projection 68 and the axial coredirection concave trench 92 b. Thereupon, the axial core conductor 7 ofthe capacitor 1 is inserted into the concave hole 96 and theelectrically-non-contact state thereof is ensured. The electrodeconductor 36 of the capacitor 1 is elastically brought into pressurecontact with one end part 94 a of the terminal member 94 andelectrically connected thereto. Similarly, the electrode conductor 37 iselastically brought into pressure contact with one end part 95 a of theterminal member 95 and electrically connected thereto. Moreover, thering-shaped projection 67 of the capacitor 1 is fitted into thering-shaped concave trench 92 a of the recess 92 of the coupling member9A and thereby the capacitor 1 is locked by the coupling member 9A.

The side of the push switch 118A, where one terminal 118Aa and the otherterminal 118Ab of the push switch 118 A shown in FIG. 8E are formed, isinserted into the recess 93 of the coupling member 9A in the state inwhich alignment in the circumferential direction is achieved by theaxial core direction projection 118Ad and the axial core directionconcave trench 93 b. Thereupon, one terminal 118Aa of the push switch118A is elastically brought into pressure contact with the other endpart 94 b of the terminal member 94 and electrically connected thereto.Similarly, the other terminal 118Ab of the push switch 118A iselastically brought into pressure contact with the other end part 95 bof the terminal member 95 and electrically connected thereto. Moreover,the ring-shaped projection 118Ac of the push switch 118A is fitted intothe ring-shaped concave trench 93 a of the recess 93 of the couplingmember 9A and thereby the push switch 118A is locked by the couplingmember 9A.

In the above-described manner, a structural body is obtained by couplingthe ferrite core 104, around which the coil 105 is wound, the capacitor1, and the push switch 118A to each other by using the coupling member8A and the coupling member 9A. This structural body is housed in theoutside case 111Aa from the opposite side to the opening 111Ac,following the core body 101, the ferrite chip 102, and the O-ring 103.Thereafter, the inside case 111Ab is fitted to the outside case 111Aa,so that the position indicator 100A is formed.

In this example, as shown in FIG. 6, the configuration is so made thatthe core body 101, the ferrite chip 102, the O-ring 103, the ferritecore 104, around which the coil 105 is wound, and the coupling member 8Aare located in the smaller-diameter hollow part of the outside case111Aa. Furthermore, the inside case 111Ab is fixed after being insertedin the outside case 111Aa in such a manner that the end surface of thecoupling member 8A on the side, where the recess 82 into which thecapacitor 1 is fitted is formed, abuts against the end part of theinside case 111Ab. Therefore, the ferrite core 104 is restricted frommoving to the opposite side to the core body 101 along the axial coredirection of the case 111A because of this abutting against the endsurface of the inside case 111Ab.

The capacitor 1, the coupling member 9A, and the push switch 118A arelocated in the hollow part of the inside case 111Ab. Furthermore, a coilspring 119A is disposed on the opposite side to the core body 101 in thehollow part of the inside case 111Ab and the capacitor 1, the couplingmember 9A, and the push switch 118A are always biased toward thecoupling member 8A by this coil spring 119A. This ensures electricalcontact among the respective terminals and prevents the backlash of therespective members configuring the position indicator 100A.

Second Embodiment

In the above-described first embodiment, the capacitances Co1 and Ca toCd of the first group are separated from the capacitances Co2 and Ce toCg of the second group by dividing the common conductor patterns and thecapacitance-forming conductor patterns into two groups in the firstconductor layer 3. However, it is also possible to divide the patternsinto two groups in the second conductor layer 4 instead of dividing thepatterns into two groups in the first conductor layer 3. The secondembodiment is an example of this case.

FIGS. 9A to 10C are diagrams for explaining a configuration example ofthe second embodiment of the capacitor according to this invention. Acapacitor 1B of this second embodiment is also based on the suppositionthat it is used as a capacitor configuring a resonant circuit of aposition indicator that has the above-described pen shape and includesthe above-described push switch. In the following description, the samepart as that in the above-described first embodiment is given the samereference numeral and detailed description thereof is omitted.

The capacitor 1B is formed by winding a film capacitor 5B, which isobtained by forming a first conductor layer 3B and a second conductorlayer 4B disposed opposed to each other with the intermediary of thedielectric film 2 on the front and back surfaces of this dielectric film2 by, for example, evaporation as shown in FIGS. 9A to 9C, and aninsulating film 6B shown in FIGS. 10A to 10C as shown in FIGS. 10B and10C, so that the capacitor 1B of this second embodiment is configured asa rod-shaped component like that shown in FIG. 10C. The first conductorlayer 3B and the second conductor layer 4B are formed of, for example, ametal layer of aluminum, zinc, or an alloy of them and are formed on thedielectric film 2 by metal evaporation.

Similarly to the case of the first embodiment shown in FIGS. 1A and 1B,FIG. 9A shows the side of the front surface 2 a of the dielectric film 2in the case of the capacitor 1B of this second embodiment, on which thefirst conductor layer 3B is formed. FIG. 9B shows the side of the backsurface 2 b of the dielectric film 2 in the case of the capacitor 1B ofthis second embodiment, on which the second conductor layer 4B isformed.

In this second embodiment, as shown in 9A, the conductor pattern of thefirst conductor layer 3B includes seven capacitance-forming conductorpatterns 32Ba, 32Bb, 32Bc, 32Bd, 32Be, 32Bf, and 32Bg having the sameconfiguration as that of the capacitance-forming conductor patterns 32 ato 32 g of the first embodiment, and area-changeable conductor patterns33Ba, 33Bb, 33Bc, 33Bd, 33Be, 33Bf, and 33Bg whose number corresponds tothe number of capacitance-forming conductor patterns 32Ba to 32Bg.However, this second embodiment is different from the first embodimentin that one common conductor pattern 31B is provided for sevencapacitance-forming conductor patterns 32Ba to 32Bg and thearea-changeable conductor patterns 33Ba to 33Bg.

The area-changeable conductor patterns 33Ba to 33Bg are formed atpositions on the side of the outermost circumferential surface of thewound body of the rod-shaped capacitor 1B so that they can be subjectedto physical treatment after the capacitor 1B is made as the completedcomponent, and are formed between the common conductor pattern 31B andthe capacitance-forming conductor patterns 32Ba to 32Bg, respectively.

In this second embodiment, the area-changeable conductor patterns 33Bato 33Bg are configured by circumferentially-disposed conductor patterns34Ba, 34Bb, 34Bc, 34Bd, 34Be, 34Bf, and 34Bg extended along thecircumferential direction of the capacitor 1B formed by being wound intoa rod shape. After the capacitor 1B is made as the completed component,these circumferentially-disposed conductor patterns 34Ba to 34Bg arephysically divided in the rod-shaped capacitor 1B along the directionperpendicular to the extension direction thereof (i.e., axial coredirection of the capacitor 1B) as shown by the dotted line in FIG. 9A.Thereby, the common conductor pattern 31B and the capacitance-formingconductor patterns 32Ba to 32Bg are set to a state of being electricallydisconnected from each other. Thus, the conductor area of the firstconductor layer 3B forming the capacitance of the capacitor 1B can bechanged.

Furthermore, in this example, as shown in FIG. 9A, thecircumferentially-disposed conductor patterns 34Ba to 34Bg forming thearea-changeable conductor patterns 33Ba to 33Bg are disposed atpositions separate from the winding-finish end of the winding directionof the dielectric film 2 by a predetermined distance d in such a manneras to be arranged in one row and at equal intervals along the horizontaldirection of the dielectric film 2 (i.e., axial core direction of thecapacitor 1B). As a result, in the rod-shaped capacitor 1B, thecircumferentially-disposed conductor patterns 34Ba to 34Bg forming thearea-changeable conductor patterns 33Ba to 33Bg are disposed at the sameposition in the circumferential direction of the capacitor 1B in such amanner as to be arranged in one row along the axial core direction ofthe capacitor 1B. In this case, similarly to the above-described firstembodiment, the predetermined distance d is so selected as to satisfyd<2πr when the radius of the rod-shaped capacitor 1B is defined as r sothat all of the circumferentially-disposed conductor patterns 34Ba to34Bg may be located at the outermost circumferential part of therod-shaped capacitor 1B.

Moreover, also in this example, each of the circumferentially-disposedconductor patterns 34Ba to 34Bg forming the area-changeable conductorpatterns 33Ba to 33Bg is so formed that each of the capacitance-formingconductor patterns 32Ba to 32Bg can be individually separated from thecommon conductor pattern 31B.

In this second embodiment, the second conductor layer 4B on the side ofthe back surface 2 b of the dielectric film 2 is composed of a firstback-surface conductor pattern 42Ba provided opposed to fourcapacitance-forming conductor patterns 32Ba to 32Bd configuring a firstgroup, and a second back-surface conductor pattern 42Bb provided opposedto three capacitance-forming conductor patterns 32Be to 32Bg configuringa second group.

The first back-surface conductor pattern 42Ba and the secondback-surface conductor pattern 42Bb are formed on the side of the backsurface 2 b of the dielectric film 2 in such a manner that they areseparated by a region, in which no conductor is formed, so as to formconductor patterns that are not connected to each other.

As shown in FIG. 9B, in the first back-surface conductor pattern 42Baand the second back-surface conductor pattern 42Bb of the secondconductor layer 4B on the side of the back surface 2 b of the dielectricfilm 2, non-conductor regions 41Ba to 41Bg, in which no conductor layeris formed, are set at the positions corresponding to the respectivepositions of the area-changeable conductor patterns 33Ba to 33Bg of thefirst conductor layer 3B on the side of the front surface 2 a, which arepossibly divided (severed) after the completed component is formed, forthe reason described for the first embodiment.

In this second embodiment, when the dielectric film 2 and the insulatingfilm 6B are wound and the rod-shaped capacitor 1B is formed as shown inFIG. 10B, for example, an adhesive is applied to the respective endsurfaces in the axial core direction of this rod-shaped capacitor 1B tothereby seal the capacitor 1B and ensure quality of the moistureresistance and so forth. In addition, the circular projection 21 and adouble circular projection 23 are bent toward the respective end surfacesides so that both end parts of the axial core conductor 7 penetratingthrough the respective penetration holes 21 a, 23 c, and 23 d of thecircular projection 21 and the double circular projection 23 may beprojected to the external. The circular projection 21 and the doublecircular projection 23 are bonded to the respective end surfaces by theapplied adhesive. Furthermore, adhesive-applied parts 21 b, 23 e, and 23f formed as extensions of the circular projection 21 and the doublecircular projection 23 are fixed to the circumferential side surface ofthe rod-shaped body by, for example, bonding. Due to this, theelectrodes of the capacitor are disposed on the circular projection 21and the double circular projection 23, and the circular projections 21and 23 function as lid parts for the winding end surfaces of thecapacitor 1B. In the circular projection 21, similarly to the firstembodiment, the penetration hole 21 a, through which the axial coreconductor 7 penetrates, and the adhesive-applied part 21 b are formedand the conductor electrode 35 extended from the common conductor 31B isformed. On the other hand, the double circular projection 23 of thissecond embodiment is composed of two circular projections 23 a and 23 bextended along the axial core direction. On the double circularprojection 23, on the side of the back surface 2 b of the dielectricfilm 2, electrode conductors 38 and 39 extended from the firstback-surface conductor pattern 42Ba and the second back-surfaceconductor pattern 42Bb, respectively, are so formed as to be notconnected to each other. As shown in FIG. 9B, the electrode conductors38 and 39 are each formed by connecting two half-ring-shaped conductorson two circular projections 23 a and 23 b.

Because of being formed on the side of the back surface 2 b of thedielectric film 2, the electrode conductors 38 and 39 can be used as anelectrode conductor exposed at an end surface in the axial coredirection of the rod-shaped capacitor 1B by folding back two circularprojections 23 a and 23 b at the boundary line thereof to make themoverlap with each other and preferably fixing them to each other by anadhesive. Specifically, after the dielectric film 2 is wound into a rodshape, first the circular projection 23 a is folded back to the side ofthe winding end surface on which the adhesive is applied. Next, thecircular projection 23 b is folded back to the opposite side to beoverlapped with the circular projection 23 a and each other's opposingsurfaces are fixed by the adhesive. At this time, the circularprojections are folded back to be overlapped with each other in such amanner that the penetration hole 23 c of the circular projection 23 aand the penetration hole 23 d of the circular projection 23 b, througheach of which the axial core conductor 7 penetrates, are at the sameposition.

Due to this, at one end surface of the capacitor 1B wound into a rodshape, the electrode conductors 38 and 39 are exposed to the externaland the axial core conductor 7 penetrating through the penetration holes23 c and 23 d is projected. The adhesive-applied parts 23 e and 23 f areformed in the double circular projection 23 and are bonded to thecircumferential side surface of the rod-shaped capacitor 1B. Thereby,the double circular projection 23 is fixed to the end surface of thecapacitor 1B.

Furthermore, in this second embodiment, as shown in FIGS. 10A to 10C, onthe winding-finish end side of the insulating film 6B wound togetherwith the film capacitor 5B, which is the side of a surface 6Ba exposedto the external after the winding finish, division marks 61Ba to 61Bgare formed by, for example, printing and are displayed at the positionsthat correspond to the respective positions of thecircumferentially-disposed conductor patterns 34Ba to 34Bg configuringthe area-changeable conductor patterns 33Ba to 33Bg formed in the firstconductor layer 3B on the dielectric film 2 when the insulating film 6Bis overlapped on the dielectric film 2 and wound. Near the respectivedivision marks 61Ba to 61Bg, capacitance values according to therespective areas of the capacitance-forming conductor patterns 32Ba to32Bg, which are electrically disconnected and separated when thecircumferentially-disposed conductor patterns 34Ba to 34Bg configuringthe area-changeable conductor patterns 33Ba to 33Bg, respectively, aredivided, are marked by printing, for example.

Furthermore, circumferential position marks 62Ba and 62Bb are formed byprinting, for example, and are displayed in order to indicate thecircumferential position of the circumferentially-disposed conductorpatterns 34Ba to 34Bg configuring the area-changeable conductor patterns33Ba to 33Bg. The division marks 61Ba to 61Bg and the capacitance valuesare disposed and displayed in one row at equal intervals along the axialcore direction of the rod-shaped capacitor 1B as shown in FIGS. 10A and10C.

As shown in FIG. 10B, also in this example, near the winding-finish endof the surface 2 b of the dielectric film 2 configuring the filmcapacitor 5B, a division block sheet 65B is formed by deposition in apartial region having a length D, equal to or larger than the lengthcorresponding to the whole circumference of the capacitor 1B, from thiswinding-finish end. The division of the circumferentially-disposedconductor patterns 34Ba to 34Bg configuring the area-changeableconductor patterns 33Ba to 33Bg is performed from the side of thesurface 6Ba of the insulating film 6B in FIGS. 10A to 10C. In order toblock the wound part located under the circumferentially-disposedconductor patterns 34Ba to 34Bg from being divided by this division, thedivision block sheet 65B having the predetermined length D is formed bydeposition near the winding-finish end of the surface 2 b of thedielectric film 2 configuring the film capacitor 5B corresponding to thepositions at which the circumferentially-disposed conductor patterns aredisposed.

[Equivalent Circuit of Capacitor 1B]

The equivalent circuit of the capacitor 1B of the second embodiment withthe above-described configuration is shown in FIG. 11 and is surroundedby the dotted line. In this FIG. 11, Co1′ and Co2′ are capacitances thatare formed by opposing of the common conductor pattern 31B of the firstconductor layer 3B to the first back-surface conductor pattern 42Ba andthe second back-surface conductor pattern 42Bb of the second conductorlayer 4B, with the intermediary of the dielectric film 2, and that areaccording to the respective areas of the first back-surface conductorpattern 42Ba and the second back-surface conductor pattern 42Bb.

Ca to Cd are capacitances that are formed by opposing of thecapacitance-forming conductor patterns 32Ba to 32Bd of the firstconductor layer 3B, respectively, to the first back-surface conductorpattern 42Ba of the second conductor layer 4B, with the intermediary ofthe dielectric film 2, and that are according to their respective areas.Ce to Cg are capacitances that are formed by opposing of thecapacitance-forming conductor patterns 32Be to 32Bg of the firstconductor layer 3B, respectively, to the second back-surface conductorpattern 42Bb of the second conductor layer 4B, with the intermediary ofthe dielectric film 2, and that are according to their respective areas.

In this second embodiment, the axial core conductor 7 is connected toonly the first back-surface conductor pattern 42Ba of the secondconductor layer 4B on the side of the back surface 2 b of the dielectricfilm 2. Furthermore, the axial core conductor 7 is connected to theelectrode conductor 38 via the first back-surface conductor pattern42Ba.

On the other hand, in this second embodiment, the electrode conductor 35is connected to the common conductor pattern 31B, to which all of thecapacitance-forming conductor patterns 32Ba to 32Bg are connected viathe circumferentially-disposed conductor patterns 34Ba to 34Bgconfiguring the area-changeable conductor patterns 33Ba to 33Bg. Thesecond back-surface conductor pattern 42Bb opposed to thecapacitance-forming conductor patterns 32Be to 32Bg configuring thecapacitance of the second group is connected to the electrode conductor39.

Therefore, as shown in FIG. 11, the capacitance Co1′ according to theopposing area between the common conductor pattern 31B and the firstback-surface conductor pattern 42Ba and the capacitances Ca to Cdaccording to the areas of the capacitance-forming conductor patterns32Ba to 32Bd are connected in parallel to each other between the axialcore conductor 7, connected to the first back-surface conductor pattern42Ba of the second conductor layer 4B, and the ring-shaped electrodeconductor 35.

When any of the circumferentially-disposed conductor patterns 34Ba to34Bd configuring the area-changeable conductor patterns 33Ba to 33Rd isdivided as described above, this divided capacitance among thecapacitances Ca to Cd connected in parallel to the capacitor Co1′ is cutat the position indicated by the dotted line in FIG. 11 to becomedisconnected. Thus, the capacitance between the axial core conductor 7and the ring-shaped electrode conductor 35, as the respective electrodesof the capacitor, decreases by this disconnected capacitance.

When the electrode conductor 38 is electrically connected to theelectrode conductor 39 by the push switch 118A, for example, the firstback-surface conductor pattern 42Ba and the second back-surfaceconductor pattern 42Bb of the second conductor layer 4B are connected tothe axial core conductor 7. This provides the state in which thecapacitance Co1′, the capacitance Co2′ according to the opposing areabetween the second back-surface conductor pattern 42Bb and the commonconductor pattern 31B, and the capacitances Ca to Cg according to theareas of the capacitance-forming conductor patterns 32Ba to 32Bg areconnected in parallel to each other between the axial core conductor 7and the ring-shaped electrode conductor 35.

When any of the circumferentially-disposed conductor patterns 34Be to34Bg configuring the area-changeable conductor patterns 33Be to 33Bg isdivided, this divided capacitance among the capacitances Ce to Cgconnected in parallel to the capacitor Co2′ is cut at the positionindicated by the dotted line in FIG. 11 to become disconnected. Thus,the capacitance of the capacitor 1B decreases by this disconnectedcapacitance.

Therefore, also when the capacitor 1B of this second embodiment is used,the capacitance value can be adjusted exactly as with the capacitor 1 ofthe first embodiment. If the capacitor 1B is used as a capacitor forresonant frequency adjustment of the resonant circuit in the positionindicator, it is possible to provide, with one capacitor 1B, operationand effects equivalent to those provided by a large number of capacitorsincluding the existing trimmer capacitor as described above.

[Other Examples of Position Indicator Including Capacitor 1 or Capacitor1B] First Example

The position indicator 100A, to which the capacitor 1 of theabove-described first embodiment is applied, detects frequency change(phase) based on change in the inductance value of the coil 105 inassociation with the writing pressure applied to the core body 101 tothereby detect the writing pressure.

A position indicator 100B to be described below detects the writingpressure based on change in the capacitance of a capacitor configuring aresonant circuit together with the coil 105.

FIG. 12 shows a configuration example of the position indicator 100B ofthis example. In this FIG. 12, the same part as that in the positionindicator 100A shown in FIG. 6 is given the same reference numeral anddetailed description thereof is omitted. Also in this FIG. 12, a case111B is shown in cross-section for easy explanation of the configurationwithin the case 111B.

Also in the position indicator 100B of this example, the case 111B iscomposed of a hollow cylindrical outside case 111Ba and an inside case111Bb and has a configuration in which the outside case 111Ba isconcentrically fitted to the inside case 111Bb, similarly to theposition indicator 100A. In the hollow part of the case 111B, thefollowing components are so housed as to be sequentially arranged alongthe center axis direction of the case 111B as shown in FIG. 12: a corebody 101B, a coil 105B that is as one example of an inductance elementand is wound around a ferrite core 104B as one example of a magneticbody, components 121, 122, 123, and 124 configuring avariable-capacitance capacitor to be described later for responding tothe writing pressure, the capacitor 1 of the first embodiment, and thepush switch 118A.

In this example, the above-mentioned variable-capacitance capacitor forresponding to the writing pressure in the position indicator 100B isconfigured with mechanism components such as the elastic electricalconductor 121, the dielectric 122, the coil spring 123 having electricalconductivity, and the electrical conductor 124 formed of a materiallike, for example, electrically-conductive rubber in order to detect thewriting pressure applied to the core body 101B as change in thecapacitance.

The core body 101B is housed in the case 111B together with the ferritecore 104B in such a manner that it abuts against the ferrite core 104Band its tip projects as the pen tip from an opening 111Bc of the outsidecase 111Ba. The core body 101B has a flange part 101Ba. This flange part101Ba is engaged with a step part provided around the opening 111Bc ofthe outside case 111Ba so that the core body 101B may be locked in thecase 111B.

The coil 105B is wound around the ferrite core 104B. As shown in FIG.12, a concave hole 104Ba is provided in the end surface of a flange part104Bb of the ferrite core 104B. The elastic electrical conductor 121 isformed of a material like, for example, electrically-conductive rubber.It has electrical conductivity and elasticity and has a projection 121 afitted into the concave hole 104Ba. The elastic electrical conductor 121is mounted on the end surface of the flange part 104Bb of the ferritecore 104B by fitting its projection 121 a into the concave hole 104Ba.The diameter of this elastic electrical conductor 121 is set equal tothat of the dielectric 122. By biasing the elastic electrical conductor121 toward the core body 101B by the coil spring 123 having electricalconductivity, the elastic electrical conductor 121 and the dielectric122 are disposed opposed to each other in such a manner that an air gapAr is formed between the elastic electrical conductor 121 and thedielectric 122 when the writing pressure is not applied to the core body101B. In this case, the winding diameter (inner diameter) of the coilspring 123 is set slightly larger than that of the elastic electricalconductor 121 and the dielectric 122. One axial end side of the coilspring 123 is locked near the bottom of the elastic electrical conductor121 with the elastic electrical conductor 121 and the dielectric 122housed in the coil frame of the coil spring 123, and the coil spring 123is electrically connected to the elastic electrical conductor 121. Theother end side of the coil spring 123 is electrically insulated from theelectrical conductor 124 and connected at a coupling member 8B asdescribed later.

As shown in FIG. 12, the end surface of the coupling member 8B on theside opposite to the end surface opposed to the electrical conductor 124is so configured as to abut against the end surface of the inside case111Bb. This restricts the position of the coupling member 8B in thedirection opposite to the direction of the core body 101B. Therefore,the ferrite core 104B is always elastically biased toward the core body101B by the coil spring 123. A recess 124 a for positioning is formed inthe end surface of the electrical conductor 124 on the side opposite tothe end surface, against which the dielectric 122 abuts.

The coupling member 8B is disposed in the outside case 111Ba in such amanner as to abut against the end surface of the electrical conductor124 on the side opposite to the end surface, against which thedielectric 122 abuts. As shown in FIG. 12 and FIGS. 13A to 13D to bedescribed later, in this coupling member 8B, a projection 89 d forpositioning and electrical connection to the electrical conductor 124 isformed at such a position as to be fitted into the recess 124 a formedin the electrical conductor 124. The projection 89 d formed in thecoupling member 8B is fixed by, for example, an adhesive in such a stateas to be fitted into the recess 124 a of the electrical conductor 124.

To the side of this coupling member 8B on the side opposite to the endsurface, against which the electrical conductor 124 abuts, the axial endpart of the capacitor 1 at which the electrode conductor 35 is formed isfitted. The axial end part of the capacitor 1 on the opposite side iscoupled to the push switch 118A via the coupling member 9A similarly tothe example of FIG. 6. Also in this example, the coil spring 119A isdisposed in the inside case 111Bb to always elastically bias the pushswitch 118A and the capacitor 1 toward the core body 101B. This ensureselectrical contact among the respective mechanism components andprevents the backlash of the respective mechanism components configuringthe position indicator 100B.

In the case of this example, as described later, the other end side ofthe coil spring 123 and the electrical conductor 124 are connected toone end and the other end of the coil 105B by the coupling member 8B.Thereby, the coil 105B is electrically connected in parallel to thevariable-capacitance capacitor that is formed of the elastic electricalconductor 121, the dielectric 122, the coil spring 123, and theelectrical conductor 124 so as to respond to the writing pressure.

In this example, when pressing force (writing pressure) is applied fromthe side of the core body 101B configuring the pen tip to the elasticelectrical conductor 121 via the ferrite core 104B, the end surface ofthe elastic electrical conductor 121 made to bulge into a dome shape isso biased as to get closer to and contact the end surface of thedielectric 122 against the biasing force of the coil spring 123. Thedome-shaped bulging end surface of the elastic electrical conductor 121is brought into contact with the end surface of the dielectric 122 withthe contact area depending on the pressing force. As a result, thecapacitance of the variable-capacitance capacitor configured between theelastic electrical conductor 121 and the electrical conductor 124 withthe intermediary of the dielectric 122 changes in association with thewriting pressure.

In this embodiment, because this variable-capacitance capacitor isconnected in parallel to the coil 105B to form a resonant circuit, theresonant frequency of the resonant circuit changes in association withcapacitance change depending on the writing pressure. Thus, the phase(resonant frequency) of radio waves transmitted from the coil 105 of theresonant circuit changes. Therefore, also in the case of the positionindicator 100B of this example, detection of the position and thewriting pressure is possible in the position detecting device having thecircuit configuration shown in FIG. 25.

The coupling member 9A in the position indicator 100B of this examplehas the above-described configuration of FIGS. 8A to 8E. Therefore,description thereof is omitted and a configuration example of only thecoupling member 8B will be described.

FIGS. 13A to 13D show a configuration example of the coupling member 8B.This coupling member 8B has almost the same configuration as that of thecoupling member 8A shown in FIGS. 7A to 7C. The same constituent part asthat in the coupling member 8A is given the same reference numeral anddetailed description thereof is omitted.

FIG. 13A is a diagram when the coupling member 8B is viewed from theside coupled to the electrical conductor 124. FIG. 13B is a sectionalview along line E-E in FIG. 13A. FIG. 13C is a diagram for explaininghow the capacitor 1 is coupled to the coupling member 8B coupled to theelectrical conductor 124.

As shown in FIGS. 13A and 13B, the coupling member 8B is formed of acolumnar resin member and is obtained by performing insert molding insuch a manner that a recess 82 is formed, into which the capacitor 1 isfitted, and terminal members 88 and 89 having elasticity are inserted.The terminal members 88 and 89 are for electrically connecting one end105Ba and the other end 105Bb of the coil 105B, the coil spring 123connected to the elastic electrical conductor 121 to serve as oneelectrode of the variable-capacitance capacitor and the electricalconductor 124 serving as the other electrode, and the electrodeconductor 35 and the axial core conductor 7 of the capacitor 1.

In the coupling member 8B of this example, one end parts 88 a and 89 aof the terminal members 88 and 89 are each vertically disposed along thedirection perpendicular to the circumferential direction in concavetrenches 86 and 87 formed at positions separate from each other by anangular distance of 180 degrees in the circumferential side surface ofthe columnar resin member. Furthermore, as shown in FIG. 13A, twoV-shaped notches 88 b and 88 c are formed in this vertically-disposedone end part 88 a of the terminal member 88. In addition, one V-shapednotch 89 b is formed in vertically-disposed one end part 89 a of theterminal member 89.

To one of two V-shaped notches 88 b and 88 c, one end 105Ba of the coil105B is locked and electrically connected. To the other of two V-shapednotches 88 b and 88 c, an end part 123 a of the coil spring 123electrically connected to the elastic electrical conductor 121 is lockedand electrically connected. The other end 105Bb of the coil 105B islocked and electrically connected to the V-shaped notch 89 b formed inone end part 89 a of the terminal member 89 vertically disposed in theconcave trench 87.

The terminal member 89 is inserted in the columnar resin member ininsert molding in such a manner as to form a projection 89 d thatprojects from the flat surface abutting against the electrical conductor124. This projection 89 d is fitted into the recess 124 a of theelectrical conductor 124 and thereby the terminal member 89 iselectrically connected to the electrical conductor 124. The couplingmember 8B is fixed to the electrical conductor 124 by bonding or thelike.

In the coupling member 8B, the other end part 88 d of the terminalmember 88 is so configured as to be exposed from the bottom of therecess 82. Due to this, as shown in FIG. 13C, the electrode conductor 35of the capacitor 1 is elastically brought into contact with andelectrically connected to the end part 88 d of the terminal member 88when the rod-shaped capacitor 1 is inserted into the recess 82.

The other end part 89 c of the terminal member 89 is located in aconcave hole 82 b formed at the center of the bottom of the recess 82similarly to the terminal member 84 of the coupling member 8A shown inFIGS. 7A to 7C. At the part at which the other end part 89 c of theterminal member 89 is located in this concave hole 82 b, an insertionhole 89 e with a bent part of an electrically-conductive metal havingelasticity is formed and the axial core conductor 7 of the capacitor 1can be inserted thereto.

Therefore, when the capacitor 1 is inserted in the recess 82, the axialcore conductor 7 of the capacitor 1 is inserted into the insertion hole89 e to contact with the bent part of an electrically-conductive metalhaving elasticity. This electrically connects the axial core conductor 7to the terminal member 89. The electrode conductor 35 of the capacitor 1is electrically connected to the other end part 88 d of the terminalmember 88. Furthermore, the ring-shaped projection 66 of the capacitor 1is fitted to a ring-shaped concave trench 82 a of the recess 82 of thecoupling member 8B. Thereby, the capacitor 1 is locked to the couplingmember 8B.

In this manner, via the coupling member 8B, the variable-capacitancecapacitor having the coil spring 123 connected to the elastic electricalconductor 121 and the electrical conductor 124 as its electrodes, thecoil 105 wound around the ferrite core 104, and the capacitor 1 areengaged with each other to be electrically connected to each other.

The equivalent circuit of this case is as shown in FIG. 14.Specifically, a variable-capacitance capacitor 120 composed of theelastic electrical conductor 121, the dielectric 122, the coil spring123, and the electrical conductor 124 is connected in parallel to thecoil 105B. Furthermore, a circuit configuration is obtained in which thecapacitances Co1, Co2, and Ca to Cg of the capacitor 1 are connected inparallel to this parallel circuit of the coil 105B and thevariable-capacitance capacitor 120.

Therefore, also in the position indicator 100B of this example, theresonant frequency of the resonant circuit can be optimized byperforming division treatment of the desired pattern among theaxially-disposed conductor patterns 34 a to 34 g configuring thearea-changeable conductor patterns 33 a to 33 g of the capacitor 1.

Although the capacitor 1 of the first embodiment is employed as thecapacitor configuring the resonant circuit with the coil 105B in theabove-described example of FIG. 12, it is obvious that the capacitor 1Bof the second embodiment can be similarly used.

Second Example

Next, yet another example of the position indicator including thecapacitor 1 or the capacitor 1B will be described. A position indicator100C of a second example to be described below also detects the writingpressure as change in the capacitance of a capacitor configuring aresonant circuit together with a coil 105C similarly to the positionindicator 100B of the above-described first example. However, theposition indicator 100C of this second example does not detect thewriting pressure by using a variable-capacitance capacitor obtained by acombination of plural mechanism components like that in theabove-described first example, but has the configuration that has beenpreviously proposed by the present assignee as Japanese PatentApplication No. 2012-15254 (U.S. application Ser. No. 13/728,699) anduses a semiconductor device referred to as a so-called MEMS (MicroElectromechanical System). In the position indicator 100C of this secondexample, the variable-capacitance capacitor that responds to the writingpressure is formed of a single capacitive pressure sensing semiconductordevice (hereinafter referred to as the pressure sensing device).

FIGS. 15 to 17C are diagrams for explaining a configuration example ofthe position indicator 100C of this second example. FIG. 15 is a diagramshowing a configuration example of the position indicator 100C of thisexample as a whole, and a case 111C is shown in cross-section for easyexplanation of the configuration within the case 111C. FIG. 16 is adiagram showing part of mechanism components housed inside the case111C. FIGS. 17A to 17C are diagrams for explaining the configuration ofthe pressure sensing device used in this example.

Also in the position indicator 100C of this example, the case 111C iscomposed of a hollow cylindrical outside case 111Ca and an inside case111Cb and has a configuration in which the outside case 111Ca isconcentrically fitted to the inside case 111Cb, similarly to theposition indicators 100A and 100B. In the hollow part of the case 111C,the following components are so housed as to be sequentially arrangedalong the center line direction of the case 111C as shown in FIG. 15: acore body 101C, a coil 105C that is one example of an inductance elementand is wound around a ferrite core 104C as one example of a magneticbody, a pressure sensing device 130 for writing pressure detection, thecapacitor 1 of the first embodiment, and the push switch 118A. Therespective housed components are always elastically biased toward thecore body 101C by a coil spring 119C.

In this example, the core body 101C is housed in the case 111C togetherwith the ferrite core 104C in such a manner that it abuts against theferrite core 104C and its tip projects as the pen tip from an opening111Cc of the outside case 111Ca. The core body 101C has a flange part101Ca. This flange part 101Ca is engaged with a step part providedaround the opening 111Cc of the outside case 111Ca so that the core body101C may be locked in the case 111C.

In this example, as shown in FIGS. 16A and 16B, a unit configuration ismade in which the ferrite core 104C, against which the core body 101C ismade to abut and around which the coil 105C is wound, is held by apackage 131 of the pressure sensing device 130 to provide a monolithicstructure.

FIG. 16A is a longitudinal sectional view of the unitized part composedof the core body 101C, the ferrite core 104C, around which the coil 105Cis wound, and the pressure sensing device 130. FIG. 16B is a perspectiveview for explaining the coupling part between the package 131 of thepressure sensing device 130 and the ferrite core 104C, around which thecoil 105C is wound.

As shown in FIG. 16A, a recess 104Ca, into which a projection 101Cbformed at the center of the flange part 101Ca of the core body 101C isfitted, is formed in the end surface of the ferrite core 104C on theside of the core body 101C. The projection 101Cb of the core body 101Cis press-fitted into the recess 104Ca of the ferrite core 104C and theyare fixed to each other by an adhesive, for example.

As shown in FIGS. 15 and 16A, the ferrite core 104C has a solid columnarshape in this example and the coil 105C is wound around it. Along thecenter line direction of the ferrite core 104C, a small-diameter part104Cb having a small diameter is formed on the side opposite to the corebody 101C across the wound part of the coil 105C. In this example, thediameter of the wound part of the coil 105C around the ferrite core 104Cis set to 3 mm, for example, and the diameter of the small-diameter part104Cb is set to 1 mm, for example.

The small-diameter part 104Cb of the ferrite core 104C is inserted inthe pressure sensing device 130 as a pressing member that transmits thepressure depending on the writing pressure to the pressure sensingdevice 130. Furthermore, in this example, part of the large-diameterpart of the ferrite core 104C around which the coil 105C is wound isalso held in the package 131 of the pressure sensing device 130 as shownin FIGS. 16A and 16B.

[Configuration Example of Pressure Sensing Device 130]

Next, the configuration of the pressure sensing device 130 of thisexample will be described.

In the pressure sensing device 130 of this example, a pressure detectingchip 300 configured as, for example, a semiconductor element fabricatedby a MEMS technique is sealed in the package 131 having, for example, acubic or rectangular parallelepiped box shape. Furthermore, in thisexample, the package 131 of the pressure sensing device 130 is soconfigured as to have a function as a member to mechanistically andelectrically couple the ferrite core 104C, around which the coil 105C iswound, to the capacitor 1 of the first embodiment.

The pressure detecting chip 300 detects applied pressure as change inthe capacitance and has a configuration shown in FIGS. 17A to 17C inthis example. FIG. 17B is a diagram when the pressure detecting chip 300of this example is viewed from the side of a surface 301 a that receivesa pressure P (see FIG. 17A). FIG. 17A is a sectional view along line F-Fin FIG. 17B.

As shown in FIG. 17, the pressure detecting chip 300 of this example hasa rectangular parallelepiped shape of depth×width×height=L×L×H. In thisexample, L=1.5 mm and H=0.5 mm.

The pressure detecting chip 300 of this example is composed of a firstelectrode 301, a second electrode 302, and an insulating layer(dielectric layer) 303 between the first electrode 301 and the secondelectrode 302. The first electrode 301 and the second electrode 302 areformed of a conductor composed of single-crystal silicon (Si) in thisexample. The insulating layer 303 is formed of an insulating filmcomposed of an oxide film (SiO₂) in this example. The insulating layer303 does not need to be formed of an oxide film and may be formed ofanother insulating object.

On the side of the surface of this insulating layer 303 opposed to thefirst electrode 301, a circular recess 304 centered at the centerposition of this surface is formed in this example. By this recess 304,a space 305 is formed between the insulating layer 303 and the firstelectrode 301. In this example, the bottom surface of the recess 304 isa flat surface and the diameter R thereof is set to, for example, R=1mm. Furthermore, the depth of the recess 304 is set to several tens ofmicrons to several hundreds of microns in this example.

The pressure detecting chip 300 of this example is fabricated by asemiconductor process in the following manner. First, the insulatinglayer 303 formed of an oxide film is formed on single-crystal siliconconfiguring the second electrode 302. Next, the recess 304 is formed bydisposing a mask covering the part other than the circular part with thediameter R and performing etching so that the space 305 may be formed inthis insulating layer 303 of the oxide film. Then, single-crystalsilicon configuring the first electrode 301 is deposited on theinsulating layer 303. Thereby, the pressure detecting chip 300 havingthe space 305 below the first electrode 301 is formed.

The existence of this space 305 allows the first electrode 301 to be sodisplaced as to bend toward the space 305 when being pressed from theside of the surface 301 a on the side opposite to the surface opposed tothe second electrode 302. The thickness t of the single-crystal siliconas an example of the first electrode 301 is set to such a thickness asto allow bending by the applied pressure P and is set smaller than thethickness of the second electrode 302. As described hereunder, thisthickness t of the first electrode 301 is selected so that the bendingdisplacement characteristic of the first electrode 301 against theapplied pressure P will be a desired one.

The pressure detecting chip 300 having the above-described configurationis a capacitor in which capacitance Cv is formed between the firstelectrode 301 and the second electrode 302. When the pressure P isapplied to the first electrode 301 from the side of the surface 301 a ofthe first electrode 301 on the side opposite to the surface opposed tothe second electrode 302 as shown in FIG. 17A, the first electrode 301bends as shown by the dotted line in FIG. 17A and the distance betweenthe first electrode 301 and the second electrode 302 is shortened. Thus,the value of the capacitance Cv changes to become larger. The amount ofbending of the first electrode 301 changes depending on the magnitude ofthe applied pressure P. Therefore, the capacitance Cv changes dependingon the magnitude of the pressure P applied to the pressure detectingchip 300 as shown in an equivalent circuit of FIG. 17C.

It is confirmed that bending by several microns is caused by pressure inthe single-crystal silicon shown as an example of the first electrode301 and the capacitance Cv of the capacitor shows a change of 0 to 100pF (picofarad) depending on the pressing force P of the writing pressurein association with this bending.

In the pressure sensing device 130 of this embodiment, the pressuredetecting chip 300 having the above-described configuration is housed inthe package 131 in the state in which the surface 301 a of the firstelectrode 301, which receives pressure, is opposed to a top surface 131a of the package 131 in FIGS. 15, 16A, and 16B.

In this example, the package 131 is composed of a package member 132formed of an electrical insulating material such as a ceramic materialand a resin material and an elastic member 133 provided on the side ofthe surface 301 a, across which the pressure detecting chip 300 receivespressure, in this package member 132. The elastic member 133 is oneexample of a pressure transmitting member having predeterminedelasticity.

Furthermore, in this example, a recess 132 a corresponding to the areaof the first electrode 301 is made at part above the surface 301 a ofthe first electrode 301, across which the pressure detecting chip 300receives pressure, in the package member 132, and the elastic member 133is so disposed as to be packed in this recess 132 a. The elastic member133 is formed of a silicone resin in this example.

In the package 131, a communication hole 134 that communicates from thetop surface 131 a to part of the elastic member 133 is formed.Specifically, a penetration hole 132 b configuring part of thecommunication hole 134 is formed in the package member 132 and a concavehole 133 a configuring the end part of the communication hole 134 ismade in the elastic member 133. Furthermore, a taper part 132 c isformed on the side of the opening part of the communication hole 134 ofthe package member 132 (on the side of the top surface 131 a) and theopening part of the communication hole 134 is formed in a trumpet shape.

As shown in FIGS. 15, 16A, and 16B, the small-diameter part 104Cb of theferrite core 104C is inserted in the communication hole 134 for thepressure sensing device 130. In this case, the pressure P depending onthe writing pressure applied to the core body 101C serving as the pentip part is transmitted to the pressure detecting chip 300 of thepressure sensing device 130 along the axial core direction (center linedirection) of the ferrite core 104C. In this example, the inner diameterof the penetration hole 132 b of the package member 132 is set slightlylarger than the diameter of the part of the small-diameter part 104Cb ofthe ferrite core 104C abutting against the penetration hole 132 b. Inaddition, the inner diameter of the concave hole 133 a of the elasticmember 133 is set slightly smaller than the diameter of the part of thesmall-diameter part 104Cb of the ferrite core 104C abutting against theconcave hole 133 a. This provides a configuration in which guiding ofthe small-diameter part 104Cb of the ferrite core 104C to the inside ofthe pressure sensing device 130 is facilitated by the taper part 132 cand the penetration hole 132 b and the ferrite core 104C, whosesmall-diameter part 104Cb is inserted in the pressure sensing device130, is so held as not to easily drop off.

Specifically, because the opening part of the communication hole 134 hasa trumpet shape, the small-diameter part 104Cb of the ferrite core 104Cis guided by the taper part 132 c at this opening part to be easily ledand inserted into the communication hole 134. Furthermore, thesmall-diameter part 104Cb of the ferrite core 104C is pushed to theinside of the concave hole 133 a of the elastic member 133 at the endpart of the communication hole 134. In this manner, the small-diameterpart 104Cb of the ferrite core 104C is inserted into the communicationhole 134 of the pressure sensing device 130 to thereby be positioned insuch a state as to apply the pressure P along the axial core directionto the side of the surface across which the pressure detecting chip 300receives pressure.

In this case, because the inner diameter of the concave hole 133 a isslightly smaller than the diameter of the part of the small-diameterpart 104Cb of the ferrite core 104C abutting against the concave hole133 a, the small-diameter part 104Cb of the ferrite core 104C becomessuch a state as to be elastically held by the elastic member 133 in theconcave hole 133 a of the elastic member 133. That is, when beinginserted in the communication hole 134 of the pressure sensing device130, the small-diameter part 104Cb of the ferrite core 104C is held bythe pressure sensing device 130.

In this example, the package 131 of the pressure sensing device 130 has,on the side of the top surface 131 a, a recess 131 c for fitting andholding of part of the coil-wound part of the ferrite core 104C. Thepackage 131 holds the ferrite core 104C in the state in which thesmall-diameter part 104Cb of the ferrite core 104C is inserted in thecommunication hole 134 of the package 131 and part of the coil-woundpart of the ferrite core 104C is fitted to the recess 131 c.

In this case, a cushion member 135 is provided between the step part,which is made by the coil-wound part and the small-diameter part 104Cbof the ferrite core 104C, and the bottom of the recess 131 c of thepackage 131 of the pressure sensing device 130, in order to preventlimiting of bending of the first electrode 301 of the pressure detectingchip 300 toward the space 305 by the small-diameter part 104Cb of theferrite core 104C based on applied pressure. It is also possible thatthe package member 132 configuring the package 131 is formed by the samematerial as that of the elastic member 133, specifically, for example, asilicone resin.

Furthermore, as shown in FIG. 15, the core body 101C, the ferrite core104C, and the pressure sensing device 130 are housed in the case 111C insuch a manner that an end surface 131 b of the pressure sensing device130 on the opposite side to the side coupled to the ferrite core 104C islocked by the end surface of the inside case 111Cb so that the pressuresensing device 130 may be prevented from moving along the axial coredirection of the position indicator 100C.

In the above-described configuration, when pressing force is applied tothe pen tip side of the position indicator 100C along the axial coredirection, i.e., when a writing pressure is applied, the ferrite core104C presses the pressure detecting chip 300 via the elastic member 133of the pressure sensing device 130 by the pressure depending on thiswriting pressure. As described above, the capacitance Cv of the pressuredetecting chip 300 changes depending on the writing pressure transmittedto the pressure detecting chip 300.

In this case, as shown in FIG. 16A, the pressure is applied to the firstelectrode 301 via the elastic member 133 on the side of the surface 301a, which receives the pressure. This causes the pressure detecting chip300 to show the capacitance Cv depending on the writing pressure appliedby the small-diameter part 104Cb of the ferrite core 104C.

In this case, the side of the surface across which the pressuredetecting chip 300 receives the pressure is not directly pressed by thesmall-diameter part 104Cb of the ferrite core 104C and the elasticmember 133 exists between the small-diameter part 104Cb of the ferritecore 104C and the pressure detecting chip 300. This enhances thepressure resistance and shock resistance on the side of the surfaceacross which the pressure detecting chip 300 receives the pressure andcan prevent this surface side from being broken by excessive pressure,unexpected instantaneous pressure, etc. That is, in the pressure sensingdevice 130, the pressure detecting chip 300 receives the pressure by thewriting pressure via the elastic member 133 as the pressure transmittingmember having predetermined elasticity. Therefore, the pressure sensingdevice 130 has pressure resistance and shock resistance against thepressure applied to the pressure detecting chip 300, specifically thefirst electrode 301, which receives the pressure.

Furthermore, the small-diameter part 104Cb of the ferrite core 104C isinserted in and guided by the communication hole 134 made in the package131 of the pressure sensing device 130 to thereby be positioned.Therefore, the applied writing pressure is surely transmitted to thepressure detecting chip 300 via the elastic member 133.

The applied writing pressure is transmitted as a pressure to the surface301 a of the first electrode 301 of the pressure detecting chip 300 bythe elastic member 133. Therefore, the applied writing pressure issurely applied to the surface 301 a, across which the pressure detectingchip 300 receives the pressure, and the pressure sensing device 130shows capacitance change corresponding to the writing pressure P. Thispermits favorable detection of the writing pressure.

At the part of the package 131 on the side opposite to the side engagedwith the ferrite core 104C, a recess 136 is formed, to which thecapacitor 1 is fitted along the axial core direction. This recess 136has an inner diameter almost equal to the outer diameter of thecapacitor 1 and a ring-shaped concave trench 136 a is formed in thesidewall thereof, to which the ring-shaped projection 66 of thecapacitor 1 is fitted.

Similarly to the above-described coupling member 8B, terminal members137 and 138 formed of an electrical conductor having elasticity are ledout at the bottom of the recess 136 of the package 131 through insertmolding. They are so configured that both ends of the coil 105C, thefirst and second electrodes 301 and 302 of the variable capacitorconfiguring the pressure detecting chip 300, and the electrode conductor35 and the axial core conductor 7 of the capacitor 1 are connected toeach other.

Specifically, an end part 137 a of the terminal member 137 connected tothe first electrode 301 of the pressure detecting chip 300 is so led outas to be exposed on the bottom surface of the recess 136. The electricalconnection of this terminal member 137 to the first electrode 301 of thepressure detecting chip 300 is made by, for example, a gold wire.

A concave hole 136 b is formed in the bottom surface of this recess 136.One end 138 a of the terminal member 138 connected to the secondelectrode 302 of the pressure detecting chip 300 is located in thisconcave hole 136 b. The terminal member 138 is attached in contact withthe second electrode 302 of the pressure detecting chip 300 to therebybe electrically connected to the second electrode 302.

Around the end part 138 a of the terminal member 138 located in theconcave hole 136 b, an insertion hole 138 b with a bent part of anelectrically-conductive metal having elasticity is formed, whereby theprojecting part of the axial core conductor 7 of the capacitor 1 can beinserted therein.

Therefore, when the capacitor 1 is inserted in the recess 136 of thepackage 131 of the pressure sensing device 130, the axial core conductor7 of the capacitor 1 is inserted in the insertion hole 138 b so as tocontact the bent part of an electrically-conductive metal havingelasticity. This electrically connects the axial core conductor 7 to theterminal member 138. At this time, simultaneously the electrodeconductor 35 of the capacitor 1 abuts against the end part 137 a of theterminal member 137 and thereby they are electrically connected to eachother. Furthermore, the ring-shaped projection 66 of the capacitor 1 isfitted to the ring-shaped concave trench 136 a of this recess 136 andthereby the capacitor 1 is locked to the package 131.

In this example, as shown in FIGS. 16A and 16B, terminals 139 a and 139b electrically connected to the terminal members 137 and 138,respectively, by, for example, a gold wire (shown by the thin solidline) are provided on the top surface 131 a of the package 131. To theseterminals 139 a and 139 b, one end 105Ca and the other end 105Cb,respectively, of the coil 105C wound around the ferrite core 104C areconnected.

Based on the above-described configuration, the capacitor 1 is insertedand fitted into the recess 136 of the resonant circuit unit obtained bymonolithically configuring the ferrite core 104C, on which the core body101C is disposed and around which the coil 105C is wound, and thepressure sensing device 130. This connects the electrode conductor 35and the axial core conductor 7 of the capacitor 1 to one end 105Ca andthe other end 105Cb, respectively, of the coil 105C, and also to thefirst electrode 301 and the second electrode 302, respectively, of thepressure detecting chip 300.

Therefore, this position indicator 100C also has a circuit configurationsimilar to that of the equivalent circuit shown in FIG. 14.

Coupling of the capacitor 1 to the push switch 118A in this positionindicator 100C is made by the coupling member 9A similarly to theposition indicator 100B of the above-described embodiment. Therefore,description thereof is omitted here.

As described above, also in the position indicator 100C of this example,the resonant frequency of the resonant circuit can be set to the desiredfrequency by performing division treatment for the necessary patternsamong the axially-disposed conductor patterns 34 a to 34 g configuringthe area-changeable conductor patterns 33 a to 33 g of the capacitor 1.

Although the capacitor 1 of the first embodiment is employed as thecapacitor configuring the resonant circuit with the coil 105C in theabove-described example of FIG. 15, it is obvious that the capacitor 1Bof the second embodiment can be similarly used.

Modification Examples of First Embodiment or Second Embodiment

<Modification Examples of Capacitance-Forming Conductor Patterns>

In the capacitor 1 of the first embodiment and the capacitor 1B of thesecond embodiment described above, the plural capacitance-formingconductor patterns 32 a to 32 g and 32Ba to 32Bg are made the same inthe width W along the winding axial core direction of the dielectricfilm 2 (film capacitor 5) and are made different in the length along thewinding direction. Thereby, their areas are made different and thevalues of the capacitance formed with the conductor layer 4 on the backsurface side are made different from each other.

However, it is obvious that the plural capacitance-forming conductorpatterns are not limited to those having such shape and size and variouspattern shapes and sizes can be employed.

FIG. 18A shows one example thereof. In this example, the widths, alongthe winding axial core direction, of plural capacitance-formingconductor patterns 32Ca to 32Cg formed on one surface 2 a of thedielectric film 2 are set to different widths W1, W2, W3, W4, W5, W6,and W7 and the lengths thereof along the winding direction are set tothe same length Lc. Thereby, their areas are made different.

In this example of FIG. 18A, area-changeable conductor patterns 33Ca to33Cg including circumferentially-disposed conductor patterns 34Ca to34Cg are provided between a common conductor pattern 31C and the pluralcapacitance-forming conductor patterns 32Ca to 32Cg. However, it isobvious that in this example of FIG. 18A also, patterns includingaxially-disposed conductor patterns, instead, may be employed as thearea-changeable conductor patterns formed between the common conductorpattern 31C and the plural capacitance-forming conductor patterns 32Cato 32Cg.

FIG. 18B shows another example of the plural capacitance-formingconductor patterns. In this example, plural capacitance-formingconductor patterns 32Da to 32Dh all having the same width W and the samelength Ld are formed on one surface 2 a of the dielectric film 2. In thecase of this example, all of the values of the capacitance configured bythe capacitance-forming conductor patterns 32Da to 32Dh are the same ifthe conductor layer 4 is uniformly formed on the back surface side ofthe dielectric film 2. Therefore, although adjustment of the capacitanceis rough, the adjustment is enabled by only deciding the number ofdivided capacitance-forming conductor patterns. Therefore, there is anadvantage that the setting of the capacitance becomes correspondinglyeasy.

In this example of FIG. 18B, area-changeable conductor patterns 33Da to33Dh including axially-disposed conductor patterns 34Da to 34Dh areprovided between a common conductor pattern 31D and the pluralcapacitance-forming conductor patterns 32Da to 32Dh. Furthermore, inconsideration of the case in which the width W is comparatively small,the axially-disposed conductor patterns 34Da to 34Dh are not disposed atthe same position in the circumferential direction and are alternatelyshifted (offset) from each other.

In the above-described example of FIG. 18A, the division (severance)direction is the axial core direction shown by the dotted line in FIG.18A and the possible division positions are close to each other when thecapacitance-forming conductor patterns having small widths are adjacentto each other. In the example of FIG. 18B, the division positions can beset more distant from each other in the area-changeable conductorpatterns adjacent to each other by making the division positionsdifferent in the axial core direction and the circumferential direction.

It is obvious that, in this example of FIG. 18B, patterns includingcircumferentially-disposed conductor patterns may be employed as thearea-changeable conductor patterns formed between the common conductorpattern 31D and the plural capacitance-forming conductor patterns 32Dato 32Dg.

Moreover, the plural capacitance-forming conductor patterns are notlimited to those having rectangular shapes like in the above-describedexamples. For example, as shown in an example of FIG. 19, pluralcapacitance-forming conductor patterns 32Ea to 32Eg having patternshapes different from each other may be formed on one surface 2 a of thedielectric film 2.

In this example of FIG. 19, area-changeable conductor patterns 33Ea to33Eg including circumferentially-disposed conductor patterns 34Ea to34Eg are provided between a common conductor pattern 31E and pluralcapacitance-forming conductor patterns 32Ea to 32Eg. However, it isobvious that patterns including axially-disposed conductor patterns maybe employed as the area-changeable conductor patterns formed between thecommon conductor pattern 31E and the plural capacitance-formingconductor patterns 32Ea to 32Eg also in this example of FIG. 19.

<Other Examples of Pattern of Conductor Electrodes Connected to PushSwitch>

In the capacitors 1 and 1B of the above-described first and secondembodiments, electrodes having a half-ring shape with the same diameterare employed as the pattern of the conductor electrodes connected to thepush switch 118A as a switch circuit. Therefore, the conductorelectrodes may not be correctly electrically connected to one end andthe other end of the push switch 118A unless they are properlypositioned in the circumferential direction. That is why theabove-described positioning by use of the projection along the axialcore direction and the concave trench is carried out.

FIGS. 20A to 20C show examples in which the conductor electrode patternis so configured that such positioning can be made easy or unnecessary.The examples of FIGS. 20A to 20C are the case of application to twoconductor electrodes extended from the first common conductor pattern 31a and the second common conductor pattern 31 b to the circularprojection 22 in the capacitor 1 of the first embodiment.

FIG. 20A shows a first example thereof. In this first example, for thefirst common conductor pattern 31 a, a ring-shaped conductor electrode37R connected to this first common conductor pattern 31 a is formed onthe circular projection 22. This ring-shaped conductor electrode 37R hasa small diameter and is separate from the center hole 22 a.

For the second common conductor pattern 31 b, a ring-shaped conductorelectrode 36Ra having a large diameter is so formed as to be connectedto this second common conductor pattern 31 b and separate from thering-shaped conductor electrode 37R.

According to this example of FIG. 20A, the conductor pattern of thering-shaped conductor electrode 36Ra is partially divided (cut) by thefirst common conductor pattern 31 a so that the ring-shaped conductorelectrode 36Ra may be prevented from intersecting with the part of thethin conductor pattern extending from the first common conductor pattern31 a to be connected to the ring-shaped conductor electrode 37R.However, this divided (cut) part is small. Thus, the ring-shapedconductor electrode 37R can be separated from the ring-shaped conductorelectrode 36Ra along almost the entire angular range, and the connectionthereof to one end and the other end of the push switch 118A can bereadily made. Therefore, there is an advantage that the accuracy of thepositioning in the circumferential direction is not strictly needed ascompared to the capacitor 1 of the first embodiment and the capacitor 1Bof the second embodiment.

FIGS. 20B and 20C show a second example. In the above-describedembodiment, a winding axis such as the axial core conductor 7 is notused as the electrode on the side of the circular projection 22. Thissecond example is an example of the case in which the winding axis ofthe capacitor 1 is used as the electrode.

In this second example, as the winding axis, the first axial coreconductor 7 having an end part projected to the side of the circularprojection 21 and a second axial core conductor 70 as a different bodyelectrically disconnected from this first axial core conductor 7 areused, although not shown in the diagram. An insulating coating is madeor an insulating sheet is wound around the part of the second axial coreconductor 70 other than the part projecting from the side of thecircular protrusion 22 so that this part is electrically disconnectedfrom the second conductor layer 4 formed on the back surface 2 b of thedielectric film 2.

When the rod-shaped capacitor 1 is formed and the circular projection 22is bent and fixed to its end surface, the metal conductor part of thesecond axial core conductor 70 is projected to the external through thepenetration hole 22 a of the circular projection 22 as shown in FIG.20C.

In this second example, for the second common conductor pattern 31 b, aring-shaped conductor electrode 36Rb partially notched is formed on thecircular projection 22 by extending the conductor pattern from thesecond common conductor pattern 31 b similarly to the first example.

For the first common conductor pattern 31 a, a conductor pattern 37Lconnected to the first common conductor pattern 31 a is so formed as tobe extended to the penetration hole 22 a of the circular projection 22so as to be electrically connected to the second axial core conductor 70projecting from the penetration hole 22 a of the circular projection 22by soldering or the like.

Therefore, the part of the axial core conductor 70 projecting from thecircular projection 22 can be used as the electrode in the case of thisexample. Furthermore, when this axial core conductor 70 is formed by aninsulator such as a resin material or when the diameter of this axialcore conductor 70 is small, a tubular conductor adapter 71 shown in FIG.20C can be used as the electrode by covering the second axial coreconductor 70 with it and then electrically connecting them by solderingor the like.

This second example of FIGS. 20B and 20C also achieves the sameoperation and effects as those of the first example of FIG. 20A. Inaddition, it also provides an effect that the same configuration, whichis based on an axial core conductor and a conductor pattern electrodearound it, can be employed as the electrode structure for both ends ofthe capacitor 1.

Third Embodiment

In both of the above-described embodiments, the area-changeableconductor pattern is so configured that the capacitance-formingconductor pattern is isolated from the common conductor pattern bydividing (cutting) the conductor pattern and thereby the capacitancevalue of the capacitor is changed.

In contrast, the following configuration can be employed. Specifically,capacitance-forming conductor patterns are so formed as to be dividedfrom a common conductor pattern in advance. In addition, treatment ofsoldering, connecting by a conductor, etc. is performed as physicaltreatment for changing the capacitance value. Thereby, thecapacitance-forming conductor pattern is connected to the commonconductor pattern to adjust the capacitance value.

A third embodiment is an example of this case. FIGS. 21A to 22C show aconfiguration example of a capacitor 1F of this third embodiment. Inthis third embodiment, the same part as that in the above-describedfirst embodiment is given the same reference numeral.

In this third embodiment, as shown in FIG. 21A, a first conductor layer3F is formed on the front surface 2 a of the dielectric film 2 similarlyto the capacitor 1 shown in FIGS. 1A to 1C. The first conductor layer 3Fis composed of the first common conductor pattern 31 a, the secondcommon conductor pattern 31 b, seven capacitance-forming conductorpatterns 32 a to 32 g, and area-changeable conductor patterns 33Fa to33Fg formed between the first and second common conductor patterns 31 aand 31 b and the capacitance-forming conductor patterns 32 a to 32 g,respectively.

In this third embodiment, as shown in FIG. 21A, the area-changeableconductor patterns 33Fa to 33Fg formed between the first and secondcommon conductor patterns 31 a and 31 b and the capacitance-formingconductor patterns 32 a to 32 g, respectively, include axially-dividedconductor patterns 34Fa to 34Fg in each of which a conductor pattern isdivided in the axial core direction.

As shown in FIG. 21B, a second conductor layer 4F is uniformly formed onthe side of the back surface 2 b of the dielectric film 2, including theregions opposed to the area-changeable conductor patterns 33Fa to 33Fg.

As shown in FIGS. 22A and 22B, an insulating film 6F is overlapped onthe back surface 2 b of the dielectric film 2 of the film capacitor 5Fformed of the dielectric film 2, on which the first conductor layer 3Fand the second conductor layer 4F are formed on the front and backsurfaces as described above, and they are wound into a rod shape.Thereby, the capacitor 1F shown in FIG. 22C is formed.

In this case, in the insulating film 6F, apertures 61Fa to 61Fg are madeat the positions corresponding to the axially-divided conductor patterns34Fa to 34Fg, which are the area-changeable conductor patterns 33Fa to33Fg of the conductor layer 3F on the front surface 2 a of thedielectric film 2 configuring the film capacitor 5F. Therefore, theaxially-divided conductor patterns 34Fa to 34Fg on the front surface 2 aof the dielectric film are exposed to the external through the apertures61Fa to 61Fg as shown in FIG. 22A.

As shown in FIGS. 22A and 22C, near the respective apertures 61Fa to61Fg, the capacitance values according to the respective areas of thecapacitance-forming conductor patterns 32 a to 32 g, which areelectrically disconnected due to division at the axially-dividedconductor patterns 34Fa to 34Fg as the area-changeable conductorpatterns 33Fa to 33Fg, are marked by printing, for example.

As shown in FIGS. 22A and 22C, the axially-divided conductor patterns34Fa to 34Fg as the area-changeable conductor patterns 33Fa to 33Fg areformed at the same position in the circumferential direction of therod-shaped capacitor 1F in such a manner as to be arranged in one row atequal intervals along the axial core direction of the rod-shapedcapacitor 1F. Thus, the apertures 61Fa to 61Fg are arranged in one rowat equal intervals along the axial core direction of the rod-shapedcapacitor 1F as shown in FIGS. 22A and 22C.

Although diagrammatic representation is omitted in FIGS. 22A and 22C,circumferential position marks, segment mark, axial core directionmarks, and so forth may be printed for example to be furtheradditionally displayed in relation to the apertures 61Fa to 61Fgsimilarly to the first embodiment.

In the case of the capacitor 1F of this third embodiment, adjustment insuch a direction as to increase the capacitance can be performed byconnection treatment for the axially-divided conductor patterns 34Fa to34Fg in the apertures 61Fa to 61Fg, respectively. This connectiontreatment can be performed not only manually but also as automatictreatment similarly to the above-described division treatment. Theapertures 61Fa to 61Fg, including the connected part, are sealed by aresin material or the like to maintain the quality of the moistureresistance and so forth.

In the above-described example of the third embodiment, thearea-changeable conductor patterns 33Fa to 33Fg include theaxially-divided conductor patterns 34Fa to 34Fg, in each of which apattern along the axial core direction is divided. However, they mayinclude circumferentially-divided conductor patterns, in each of which apattern along the circumferential direction is divided as describedabove.

Other Embodiments or Modification Examples

In the above-described embodiments, the axially-disposed conductorpatterns, the circumferentially-disposed conductor patterns, theaxially-divided conductor patterns, and the circumferentially-dividedconductor patterns are configured at the same position in thecircumferential direction of the rod-shaped capacitor in such a manneras to be arranged in one row along the axial core direction. However, itis also possible to dispose these patterns at different positions in thecircumferential direction.

FIGS. 23A and 23B are diagrams showing a configuration example of acapacitor 1G as one example configured in this manner. In this example,the following conductor pattern is formed as a first conductor layer 3Gon the front surface 2 a of the dielectric film 2 similarly to theabove-described embodiments. Suppose that the second conductor layer 4is almost uniformly formed on the back surface 2 b of the dielectricfilm 2.

Specifically, as shown in FIG. 23A, on the front surface 2 a of thedielectric film 2, plural capacitance-forming conductor patterns 32Ga to32Gd are formed in the winding axial core direction and a commonconductor pattern 31G is formed in common to these capacitance-formingconductor patterns 32Ga to 32Gd. Furthermore, area-changeable conductorpatterns 33Ga to 33Gd including axially-disposed conductor patterns 34Gato 34Gd, respectively, are formed between the common conductor pattern31G and the capacitance-forming conductor patterns 32Ga to 32Gd.

In the case of this example, the axially-disposed conductor patterns34Ga to 34Gd are formed at positions shifted in not only the axial coredirection but also in the circumferential direction as shown in FIG.23A. In this case, all of the axially-disposed conductor patterns 34Gato 34Gd are so formed as to exist in a region range within a distance L1from the winding-finish end of the dielectric film 2, with arelationship of L1<2πr satisfied when the radius of the rod-shapedcapacitor 1G shown in FIG. 23B is defined as r. This causes all of theaxially-disposed conductor patterns 34Ga to 34Gd to exist on theoutermost circumferential surface of the capacitor 1G as shown by thedotted lines in FIG. 23B, and enables division treatment as physicaltreatment after the completed component is formed.

FIGS. 23C and 23D are diagrams showing a configuration example of acapacitor 1H as another example. In the capacitor 1H of this example, asa first conductor layer 3H formed on the front surface 2 a of thedielectric film 2, a common conductor pattern 31H, capacitance-formingconductor patterns 32Ha to 32Hd, and area-changeable conductor patterns33Ha to 33Hd are formed, similarly to the conductor layer 3G. However,in the case of this example, the area-changeable conductor patterns 33Hato 33Hd include not axially-disposed conductor patterns butcircumferentially-disposed conductor patterns 34Ha to 34Hd,respectively.

As shown in FIG. 23C, the circumferentially-disposed conductor patterns34Ha to 34Hd are formed at the same position in the axial core directionand at different positions in the circumferential direction. Also in thecase of this example, all of the circumferentially-disposed conductorpatterns 34Ha to 34Hd are so formed as to exist in a region range withina distance L2 from the winding-finish end of the dielectric film 2, witha relationship of L2<2π satisfied. This causes all of thecircumferentially-disposed conductor patterns 34Ha to 34Hd to exist onthe outermost circumferential surface of the capacitor 1H as shown bythe dotted lines in FIG. 23D, and enables division treatment as physicaltreatment for setting the capacitance value after the completedcomponent is formed.

Although the case of axially-disposed conductor patterns andcircumferentially-disposed conductor patterns, for which divisiontreatment is performed after the completed component is formed, isdescribed with FIGS. 23A to 23D, axially-divided conductor patterns andcircumferentially-divided conductor patterns may also be so formed as tobe disposed at different positions in the circumferential direction asdescribed above.

In the above-described embodiments, the insulating film 6 is woundtogether with the film capacitor 5 in order to avoid an electricalconnection between the first conductor layer 3 and the second conductorlayer 4 on the front and back surfaces of the dielectric film 2.However, instead of using the insulating film 6, an insulating coatingmay be provided on one or both of the first conductor layer 3 and thesecond conductor layer 4 on the front and back surfaces of the filmcapacitor 5.

Alternatively, a rod-shaped capacitor may be formed in the followingmanner. Specifically, the first conductor layer 3 and the secondconductor layer 4 are formed by deposition on one surface of arespective one of two dielectric films. Then, two dielectric films arewound into the rod shape in the state in which the surface of thedielectric film including the first conductor layer 3, on which thefirst conductor layer 3 is not formed, is bonded to the surface of thedielectric film including the second conductor layer 4, on which thesecond conductor layer 4 is formed. Furthermore, the outer shape of thecapacitor wound into the rod shape may be a circular column shape, apolygonal column shape, or another shape.

In the above description, the case in which the capacitor of thisinvention is used as a capacitor of a resonant circuit in a positionindicator for adjustment of the resonant frequency of the resonantcircuit is taken as one example. However, the capacitor of thisinvention can be used for frequency adjustment or frequency tuning invarious pieces of electronic apparatus, not only in the positionindicator. For example, it can be used for various use purposes such asadjustment of the wireless transmission frequency in short-rangewireless communication apparatus, adjustment of the tuning frequency ina radio receiver, and adjustment of the tuning frequency in acontactless IC card.

DESCRIPTION OF REFERENCE SYMBOLS

104 . . . Ferrite core, 105 . . . Coil, 118, 118A . . . Push switch, 1,1B to 1H . . . Capacitor, 2 . . . Dielectric film, 3 . . . Firstconductor layer, 4 . . . Second conductor layer, 5 . . . Film capacitor,6 . . . Insulating film, 7 . . . Axial core conductor, 31 a . . . Firstcommon conductor pattern, 31 b . . . Second common conductor pattern, 32a to 32 g . . . Capacitance-forming conductor pattern, 33 a to 33 g . .. Area-changeable conductor pattern, 34 a to 34 g . . . Axially-disposedconductor pattern, 34Ba to 34Bg . . . Circumferentially-disposedconductor pattern, 34Fa to 34Fg . . . Axially-divided conductor pattern.

1. A capacitor comprising: a dielectric film; a first conductor layerand a second conductor layer which are disposed on opposite surfaces ofthe dielectric film, the dielectric film including the first and secondconductor layers being wound into a rod shape; a first electrode led outfrom the first conductor layer; and a second electrode led out from thesecond conductor layer, wherein at least one of the first conductorlayer and the second conductor layer includes a first area-changeableconductor pattern, which is disposed on an outer circumference side ofthe capacitor wound into the rod shape and which is configured toreceive physical treatment from outside to change the size of aconductor area of the at least one of the first conductor layer and thesecond conductor layer for the capacitor, such that a capacitance valueof the capacitor is selectively set corresponding to the change in theconductor area as effected by the physical treatment.
 2. The capacitoraccording to claim 1, wherein the first conductor layer includes acommon conductor pattern and a capacitance-forming conductor patternconnected to each other via the first area-changeable conductor pattern,and the physical treatment is severing the capacitance-forming conductorpattern from the common conductor pattern at the first area-changeableconductor pattern so as to decrease the capacitance value of thecapacitor.
 3. The capacitor according to claim 2, wherein the firstconductor layer includes multiple capacitance-forming conductor patternsrespectively connected to the common conductor pattern via multiplefirst area-changeable conductor patterns, and the physical treatment isselectively severing one or more of the multiple capacitance-formingconductor patterns from the common conductor pattern at thecorresponding one or more of the multiple first area-changing patterns,respectively, so as to selectively decrease the capacitance value of thecapacitor.
 4. The capacitor according to claim 1, wherein the firstconductor layer includes a common conductor pattern and acapacitance-forming conductor pattern separated from each other via thefirst area-changeable conductor pattern including a cut, and thephysical treatment is connecting the capacitance-forming conductorpattern to the common conductor pattern at the first area-changeableconductor pattern so as to increase the capacitance value of thecapacitor.
 5. The capacitor according to claim 1, wherein the firstarea-change conductor pattern is disposed on an outermost circumferenceside of the capacitor wound into the rod shape.
 6. The capacitoraccording to claim 1, wherein the first area-changeable conductorpattern is formed in one of the first conductor layer and the secondconductor layer that is disposed closer to the outer circumference sideof the capacitor wound into the rod shape.
 7. The capacitor according toclaim 1, wherein at least one first capacitance-forming conductorpattern having a predetermined area and a first common conductor patternare disposed in the at least one of the first conductor layer and thesecond conductor layer, and the first area-changeable conductor patternis disposed between the first common conductor pattern and the firstcapacitance-forming conductor pattern having the predetermined area. 8.The capacitor according to claim 7, wherein the first area-changeableconductor pattern includes an axially-disposed conductor patternextended along an axial core direction of the capacitor formed by beingwound into the rod shape, the axially-disposed conductor pattern beingconfigured to receive the physical treatment along a line thatintersects the axial core direction of the capacitor.
 9. The capacitoraccording to claim 8, wherein multiple first capacitance-formingconductor patterns are provided, and multiple first area-changeableconductor patterns each including an axially-disposed conductor patternare disposed between the first common conductor pattern and the multiplefirst capacitance-forming conductor patterns, respectively, and at leasttwo of the multiple axially-disposed conductor patterns are arranged ina row along the axial core direction of the capacitor.
 10. The capacitoraccording to claim 8, wherein multiple first capacitance-formingconductor patterns are provided, and multiple first area-changeableconductor patterns each including an axially-disposed conductor patternare disposed between the first common conductor pattern and the multiplefirst capacitance-forming conductor patterns, respectively, and themultiple axially-disposed conductor patterns are arranged atpredetermined intervals in a circumferential direction of the capacitor.11. The capacitor according to claim 7, wherein the firstarea-changeable conductor pattern includes a circumferentially-disposedconductor pattern extended along a circumferential direction of thecapacitor formed by being wound into the rod shape, thecircumferentially-disposed conductor pattern being configured to receivethe physical treatment along a line that intersects the circumferentialdirection of the capacitor.
 12. The capacitor according to claim 11,wherein multiple first capacitance-forming conductor patterns areprovided, and multiple first area-changeable conductor patterns eachincluding a circumferentially-disposed conductor pattern are disposedbetween the first common conductor pattern and the multiple firstcapacitance-forming conductor patterns, respectively, and at least twoof the multiple circumferentially-disposed conductor patterns arearranged in a row along an axial core direction of the capacitor. 13.The capacitor according to claim 11, wherein multiple firstcapacitance-forming conductor patterns are provided, and multiple firstarea-changeable conductor patterns each including acircumferentially-disposed conductor pattern are disposed between thefirst common conductor pattern and the multiple firstcapacitance-forming conductor patterns, respectively, and the multiplecircumferentially-disposed conductor patterns are arranged in a rowalong the circumferential direction of the capacitor.
 14. The capacitoraccording to claim 7, wherein the capacitance value is set byelectrically dividing the first area-changeable conductor pattern fromthe first common conductor pattern at the first area-changeableconductor pattern, or by electrically connecting the firstarea-changeable conductor pattern to the first common conductor patternat the first area-changeable conductor pattern.
 15. The capacitoraccording to claim 1, further comprising: a rod-shaped conductor, whichis disposed relative to the first conductor layer and the secondconductor layer as wound into the rod shape to be used as the firstelectrode or the second electrode of the capacitor.
 16. The capacitoraccording to claim 15, wherein the rod-shaped conductor is disposed at awinding center of the capacitor.
 17. The capacitor according to claim16, wherein one of the first conductor layer and the second conductorlayer is electrically connected to the rod-shaped conductor disposed atthe winding center of the capacitor, and the other of the firstconductor layer and the second conductor layer includes a conductorpattern that is extended along the winding center and that has apredetermined shape, and the rod-shaped conductor and the conductorpattern function as the first electrode and the second electrode. 18.The capacitor according to claim 17, wherein the conductor pattern thatis extended along the winding center and that has the predeterminedshape includes a ring-shaped conductor pattern having a center hole,through which the rod-shaped conductor projects.
 19. The capacitoraccording to claim 1, further comprising: a second area-changeableconductor pattern, which is formed in at least one of the firstconductor layer and the second conductor layer and which is configuredto be electrically severed therefrom.
 20. The capacitor according toclaim 19, wherein the second area-changeable conductor pattern is formedin the first conductor layer or the second conductor layer in which thefirst area-changeable conductor pattern is formed.
 21. The capacitoraccording to claim 20, wherein the second area-changeable conductorpattern is disposed between a second common conductor pattern and asecond capacitance-forming conductor pattern, and the second commonconductor pattern is electrically isolated from the first commonconductor pattern.
 22. The capacitor according to claim 21, wherein thefirst common conductor pattern and the second common conductor patternare disposed close to each other and are extended out along a windingcenter of the capacitor.
 23. The capacitor according to claim 22,wherein the first common conductor pattern and the second commonconductor pattern extended out along the winding center are disposed ina ring shape.
 24. The capacitor according to claim 19, wherein thesecond area-changeable conductor pattern is formed in the other of thefirst conductor layer and the second conductor layer, which is differentfrom the first conductor layer or the second conductor layer in whichthe first area-changeable conductor pattern is formed.
 25. The capacitoraccording to claim 1, further comprising: an insulating film, which iswound on the dielectric film having the first conductor layer and thesecond conductor layer to be exposed on an outer circumferential surfaceof the capacitor, and on which marking indicative of the firstarea-changeable conductor pattern is provided at a predeterminedposition on the outer circumferential surface corresponding to aposition at which the first area-changeable conductor pattern isdisposed.